From 5437926b2213b1c45c2f34bd858734de90e5fffd Mon Sep 17 00:00:00 2001 From: Gennadiy Civil Date: Tue, 17 Jul 2018 17:47:25 -0400 Subject: [PATCH] Docs sync --- googletest/docs/advanced.md | 2544 ++++++++++++++++++----------------- googletest/docs/faq.md | 1075 ++++++--------- googletest/docs/primer.md | 4 + 3 files changed, 1712 insertions(+), 1911 deletions(-) diff --git a/googletest/docs/advanced.md b/googletest/docs/advanced.md index 73b79540..6883784d 100644 --- a/googletest/docs/advanced.md +++ b/googletest/docs/advanced.md @@ -1,67 +1,77 @@ +# Advanced googletest Topics -Now that you have read [Primer](primer.md) and learned how to write tests -using Google Test, it's time to learn some new tricks. This document -will show you more assertions as well as how to construct complex -failure messages, propagate fatal failures, reuse and speed up your -test fixtures, and use various flags with your tests. +## Introduction -# More Assertions # +Now that you have read the [googletest Primer](primer) and learned how to write +tests using googletest, it's time to learn some new tricks. This document will +show you more assertions as well as how to construct complex failure messages, +propagate fatal failures, reuse and speed up your test fixtures, and use various +flags with your tests. + +## More Assertions This section covers some less frequently used, but still significant, assertions. -## Explicit Success and Failure ## +### Explicit Success and Failure -These three assertions do not actually test a value or expression. Instead, -they generate a success or failure directly. Like the macros that actually -perform a test, you may stream a custom failure message into them. +These three assertions do not actually test a value or expression. Instead, they +generate a success or failure directly. Like the macros that actually perform a +test, you may stream a custom failure message into them. -| `SUCCEED();` | -|:-------------| +```c++ +SUCCEED(); +``` -Generates a success. This does NOT make the overall test succeed. A test is +Generates a success. This does **NOT** make the overall test succeed. A test is considered successful only if none of its assertions fail during its execution. -Note: `SUCCEED()` is purely documentary and currently doesn't generate any -user-visible output. However, we may add `SUCCEED()` messages to Google Test's +NOTE: `SUCCEED()` is purely documentary and currently doesn't generate any +user-visible output. However, we may add `SUCCEED()` messages to googletest's output in the future. -| `FAIL();` | `ADD_FAILURE();` | `ADD_FAILURE_AT("`_file\_path_`", `_line\_number_`);` | -|:-----------|:-----------------|:------------------------------------------------------| - -`FAIL()` generates a fatal failure, while `ADD_FAILURE()` and `ADD_FAILURE_AT()` generate a nonfatal -failure. These are useful when control flow, rather than a Boolean expression, -determines the test's success or failure. For example, you might want to write -something like: - +```c++ +FAIL(); +ADD_FAILURE(); +ADD_FAILURE_AT("file_path", line_number); ``` + +`FAIL()` generates a fatal failure, while `ADD_FAILURE()` and `ADD_FAILURE_AT()` +generate a nonfatal failure. These are useful when control flow, rather than a +Boolean expression, determines the test's success or failure. For example, you +might want to write something like: + +```c++ switch(expression) { - case 1: ... some checks ... - case 2: ... some other checks - ... - default: FAIL() << "We shouldn't get here."; + case 1: + ... some checks ... + case 2: + ... some other checks ... + default: + FAIL() << "We shouldn't get here."; } ``` -Note: you can only use `FAIL()` in functions that return `void`. See the [Assertion Placement section](#assertion-placement) for more information. +NOTE: you can only use `FAIL()` in functions that return `void`. See the +[Assertion Placement section](#assertion-placement) for more information. -_Availability_: Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -## Exception Assertions ## +### Exception Assertions -These are for verifying that a piece of code throws (or does not -throw) an exception of the given type: +These are for verifying that a piece of code throws (or does not throw) an +exception of the given type: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_THROW(`_statement_, _exception\_type_`);` | `EXPECT_THROW(`_statement_, _exception\_type_`);` | _statement_ throws an exception of the given type | -| `ASSERT_ANY_THROW(`_statement_`);` | `EXPECT_ANY_THROW(`_statement_`);` | _statement_ throws an exception of any type | -| `ASSERT_NO_THROW(`_statement_`);` | `EXPECT_NO_THROW(`_statement_`);` | _statement_ doesn't throw any exception | +Fatal assertion | Nonfatal assertion | Verifies +------------------------------------------ | ------------------------------------------ | -------- +`ASSERT_THROW(statement, exception_type);` | `EXPECT_THROW(statement, exception_type);` | `statement` throws an exception of the given type +`ASSERT_ANY_THROW(statement);` | `EXPECT_ANY_THROW(statement);` | `statement` throws an exception of any type +`ASSERT_NO_THROW(statement);` | `EXPECT_NO_THROW(statement);` | `statement` doesn't throw any exception Examples: -``` +```c++ ASSERT_THROW(Foo(5), bar_exception); EXPECT_NO_THROW({ @@ -70,79 +80,96 @@ EXPECT_NO_THROW({ }); ``` -_Availability_: Linux, Windows, Mac; since version 1.1.0. +**Availability**: Linux, Windows, Mac; requires exceptions to be enabled in the +build environment (note that `google3` **disables** exceptions). -## Predicate Assertions for Better Error Messages ## +### Predicate Assertions for Better Error Messages -Even though Google Test has a rich set of assertions, they can never be -complete, as it's impossible (nor a good idea) to anticipate all the scenarios -a user might run into. Therefore, sometimes a user has to use `EXPECT_TRUE()` -to check a complex expression, for lack of a better macro. This has the problem -of not showing you the values of the parts of the expression, making it hard to +Even though googletest has a rich set of assertions, they can never be complete, +as it's impossible (nor a good idea) to anticipate all scenarios a user might +run into. Therefore, sometimes a user has to use `EXPECT_TRUE()` to check a +complex expression, for lack of a better macro. This has the problem of not +showing you the values of the parts of the expression, making it hard to understand what went wrong. As a workaround, some users choose to construct the failure message by themselves, streaming it into `EXPECT_TRUE()`. However, this is awkward especially when the expression has side-effects or is expensive to evaluate. -Google Test gives you three different options to solve this problem: +googletest gives you three different options to solve this problem: -### Using an Existing Boolean Function ### +#### Using an Existing Boolean Function -If you already have a function or a functor that returns `bool` (or a type -that can be implicitly converted to `bool`), you can use it in a _predicate -assertion_ to get the function arguments printed for free: +If you already have a function or functor that returns `bool` (or a type that +can be implicitly converted to `bool`), you can use it in a *predicate +assertion* to get the function arguments printed for free: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_PRED1(`_pred1, val1_`);` | `EXPECT_PRED1(`_pred1, val1_`);` | _pred1(val1)_ returns true | -| `ASSERT_PRED2(`_pred2, val1, val2_`);` | `EXPECT_PRED2(`_pred2, val1, val2_`);` | _pred2(val1, val2)_ returns true | -| ... | ... | ... | +| Fatal assertion | Nonfatal assertion | Verifies | +| -------------------- | -------------------- | --------------------------- | +| `ASSERT_PRED1(pred1, | `EXPECT_PRED1(pred1, | `pred1(val1)` is true | +: val1);` : val1);` : : +| `ASSERT_PRED2(pred2, | `EXPECT_PRED2(pred2, | `pred2(val1, val2)` is true | +: val1, val2);` : val1, val2);` : : +| `...` | `...` | ... | -In the above, _predn_ is an _n_-ary predicate function or functor, where -_val1_, _val2_, ..., and _valn_ are its arguments. The assertion succeeds -if the predicate returns `true` when applied to the given arguments, and fails +In the above, `predn` is an `n`-ary predicate function or functor, where `val1`, +`val2`, ..., and `valn` are its arguments. The assertion succeeds if the +predicate returns `true` when applied to the given arguments, and fails otherwise. When the assertion fails, it prints the value of each argument. In either case, the arguments are evaluated exactly once. Here's an example. Given -``` +```c++ // Returns true iff m and n have no common divisors except 1. bool MutuallyPrime(int m, int n) { ... } + const int a = 3; const int b = 4; const int c = 10; ``` -the assertion `EXPECT_PRED2(MutuallyPrime, a, b);` will succeed, while the -assertion `EXPECT_PRED2(MutuallyPrime, b, c);` will fail with the message - -
-!MutuallyPrime(b, c) is false, where

-b is 4

-c is 10

-
- -**Notes:** - - 1. If you see a compiler error "no matching function to call" when using `ASSERT_PRED*` or `EXPECT_PRED*`, please see [this FAQ](faq.md#the-compiler-complains-no-matching-function-to-call-when-i-use-assert_predn-how-do-i-fix-it) for how to resolve it. - 1. Currently we only provide predicate assertions of arity <= 5. If you need a higher-arity assertion, let us know. - -_Availability_: Linux, Windows, Mac. - -### Using a Function That Returns an AssertionResult ### - -While `EXPECT_PRED*()` and friends are handy for a quick job, the -syntax is not satisfactory: you have to use different macros for -different arities, and it feels more like Lisp than C++. The -`::testing::AssertionResult` class solves this problem. - -An `AssertionResult` object represents the result of an assertion -(whether it's a success or a failure, and an associated message). You -can create an `AssertionResult` using one of these factory -functions: +the assertion +```c++ + EXPECT_PRED2(MutuallyPrime, a, b); ``` + +will succeed, while the assertion + +```c++ + EXPECT_PRED2(MutuallyPrime, b, c); +``` + +will fail with the message + +```none +MutuallyPrime(b, c) is false, where +b is 4 +c is 10 +``` + +> NOTE: +> +> 1. If you see a compiler error "no matching function to call" when using +> `ASSERT_PRED*` or `EXPECT_PRED*`, please see +> [this](faq#OverloadedPredicate) for how to resolve it. +> 1. Currently we only provide predicate assertions of arity <= 5. If you need +> a higher-arity assertion, let [us](http://g/opensource-gtest) know. + +**Availability**: Linux, Windows, Mac. + +#### Using a Function That Returns an AssertionResult + +While `EXPECT_PRED*()` and friends are handy for a quick job, the syntax is not +satisfactory: you have to use different macros for different arities, and it +feels more like Lisp than C++. The `::testing::AssertionResult` class solves +this problem. + +An `AssertionResult` object represents the result of an assertion (whether it's +a success or a failure, and an associated message). You can create an +`AssertionResult` using one of these factory functions: + +```c++ namespace testing { // Returns an AssertionResult object to indicate that an assertion has @@ -156,26 +183,25 @@ AssertionResult AssertionFailure(); } ``` -You can then use the `<<` operator to stream messages to the -`AssertionResult` object. +You can then use the `<<` operator to stream messages to the `AssertionResult` +object. -To provide more readable messages in Boolean assertions -(e.g. `EXPECT_TRUE()`), write a predicate function that returns -`AssertionResult` instead of `bool`. For example, if you define -`IsEven()` as: +To provide more readable messages in Boolean assertions (e.g. `EXPECT_TRUE()`), +write a predicate function that returns `AssertionResult` instead of `bool`. For +example, if you define `IsEven()` as: -``` +```c++ ::testing::AssertionResult IsEven(int n) { if ((n % 2) == 0) - return ::testing::AssertionSuccess(); + return ::testing::AssertionSuccess(); else - return ::testing::AssertionFailure() << n << " is odd"; + return ::testing::AssertionFailure() << n << " is odd"; } ``` instead of: -``` +```c++ bool IsEven(int n) { return (n % 2) == 0; } @@ -183,77 +209,83 @@ bool IsEven(int n) { the failed assertion `EXPECT_TRUE(IsEven(Fib(4)))` will print: -
-Value of: IsEven(Fib(4))

-Actual: false (*3 is odd*)

-Expected: true

-
+```none +Value of: IsEven(Fib(4)) + Actual: false (3 is odd) +Expected: true +``` instead of a more opaque -
-Value of: IsEven(Fib(4))

-Actual: false

-Expected: true

-
- -If you want informative messages in `EXPECT_FALSE` and `ASSERT_FALSE` -as well, and are fine with making the predicate slower in the success -case, you can supply a success message: - +```none +Value of: IsEven(Fib(4)) + Actual: false +Expected: true ``` + +If you want informative messages in `EXPECT_FALSE` and `ASSERT_FALSE` as well +(one third of Boolean assertions in the Google code base are negative ones), and +are fine with making the predicate slower in the success case, you can supply a +success message: + +```c++ ::testing::AssertionResult IsEven(int n) { if ((n % 2) == 0) - return ::testing::AssertionSuccess() << n << " is even"; + return ::testing::AssertionSuccess() << n << " is even"; else - return ::testing::AssertionFailure() << n << " is odd"; + return ::testing::AssertionFailure() << n << " is odd"; } ``` Then the statement `EXPECT_FALSE(IsEven(Fib(6)))` will print -
-Value of: IsEven(Fib(6))

-Actual: true (8 is even)

-Expected: false

-
+```none + Value of: IsEven(Fib(6)) + Actual: true (8 is even) + Expected: false +``` -_Availability_: Linux, Windows, Mac; since version 1.4.1. +**Availability**: Linux, Windows, Mac. -### Using a Predicate-Formatter ### +#### Using a Predicate-Formatter If you find the default message generated by `(ASSERT|EXPECT)_PRED*` and `(ASSERT|EXPECT)_(TRUE|FALSE)` unsatisfactory, or some arguments to your predicate do not support streaming to `ostream`, you can instead use the -following _predicate-formatter assertions_ to _fully_ customize how the -message is formatted: +following *predicate-formatter assertions* to *fully* customize how the message +is formatted: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_PRED_FORMAT1(`_pred\_format1, val1_`);` | `EXPECT_PRED_FORMAT1(`_pred\_format1, val1_`);` | _pred\_format1(val1)_ is successful | -| `ASSERT_PRED_FORMAT2(`_pred\_format2, val1, val2_`);` | `EXPECT_PRED_FORMAT2(`_pred\_format2, val1, val2_`);` | _pred\_format2(val1, val2)_ is successful | -| `...` | `...` | `...` | +Fatal assertion | Nonfatal assertion | Verifies +------------------------------------------------ | ------------------------------------------------ | -------- +`ASSERT_PRED_FORMAT1(pred_format1, val1);` | `EXPECT_PRED_FORMAT1(pred_format1, val1);` | `pred_format1(val1)` is successful +`ASSERT_PRED_FORMAT2(pred_format2, val1, val2);` | `EXPECT_PRED_FORMAT2(pred_format2, val1, val2);` | `pred_format2(val1, val2)` is successful +`...` | `...` | ... -The difference between this and the previous two groups of macros is that instead of -a predicate, `(ASSERT|EXPECT)_PRED_FORMAT*` take a _predicate-formatter_ -(_pred\_formatn_), which is a function or functor with the signature: - -`::testing::AssertionResult PredicateFormattern(const char* `_expr1_`, const char* `_expr2_`, ... const char* `_exprn_`, T1 `_val1_`, T2 `_val2_`, ... Tn `_valn_`);` - -where _val1_, _val2_, ..., and _valn_ are the values of the predicate -arguments, and _expr1_, _expr2_, ..., and _exprn_ are the corresponding -expressions as they appear in the source code. The types `T1`, `T2`, ..., and -`Tn` can be either value types or reference types. For example, if an -argument has type `Foo`, you can declare it as either `Foo` or `const Foo&`, -whichever is appropriate. - -A predicate-formatter returns a `::testing::AssertionResult` object to indicate -whether the assertion has succeeded or not. The only way to create such an -object is to call one of these factory functions: - -As an example, let's improve the failure message in the previous example, which uses `EXPECT_PRED2()`: +The difference between this and the previous group of macros is that instead of +a predicate, `(ASSERT|EXPECT)_PRED_FORMAT*` take a *predicate-formatter* +(`pred_formatn`), which is a function or functor with the signature: +```c++ +::testing::AssertionResult PredicateFormattern(const char* expr1, + const char* expr2, + ... + const char* exprn, + T1 val1, + T2 val2, + ... + Tn valn); ``` + +where `val1`, `val2`, ..., and `valn` are the values of the predicate arguments, +and `expr1`, `expr2`, ..., and `exprn` are the corresponding expressions as they +appear in the source code. The types `T1`, `T2`, ..., and `Tn` can be either +value types or reference types. For example, if an argument has type `Foo`, you +can declare it as either `Foo` or `const Foo&`, whichever is appropriate. + +As an example, let's improve the failure message in `MutuallyPrime()`, which was +used with `EXPECT_PRED2()`: + +```c++ // Returns the smallest prime common divisor of m and n, // or 1 when m and n are mutually prime. int SmallestPrimeCommonDivisor(int m, int n) { ... } @@ -263,167 +295,260 @@ int SmallestPrimeCommonDivisor(int m, int n) { ... } const char* n_expr, int m, int n) { - if (MutuallyPrime(m, n)) - return ::testing::AssertionSuccess(); + if (MutuallyPrime(m, n)) return ::testing::AssertionSuccess(); - return ::testing::AssertionFailure() - << m_expr << " and " << n_expr << " (" << m << " and " << n - << ") are not mutually prime, " << "as they have a common divisor " - << SmallestPrimeCommonDivisor(m, n); + return ::testing::AssertionFailure() << m_expr << " and " << n_expr + << " (" << m << " and " << n << ") are not mutually prime, " + << "as they have a common divisor " << SmallestPrimeCommonDivisor(m, n); } ``` With this predicate-formatter, we can use -``` -EXPECT_PRED_FORMAT2(AssertMutuallyPrime, b, c); +```c++ + EXPECT_PRED_FORMAT2(AssertMutuallyPrime, b, c); ``` to generate the message -
-b and c (4 and 10) are not mutually prime, as they have a common divisor 2.

-
+```none +b and c (4 and 10) are not mutually prime, as they have a common divisor 2. +``` -As you may have realized, many of the assertions we introduced earlier are -special cases of `(EXPECT|ASSERT)_PRED_FORMAT*`. In fact, most of them are +As you may have realized, many of the built-in assertions we introduced earlier +are special cases of `(EXPECT|ASSERT)_PRED_FORMAT*`. In fact, most of them are indeed defined using `(EXPECT|ASSERT)_PRED_FORMAT*`. -_Availability_: Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. +### Floating-Point Comparison -## Floating-Point Comparison ## - -Comparing floating-point numbers is tricky. Due to round-off errors, it is -very unlikely that two floating-points will match exactly. Therefore, -`ASSERT_EQ` 's naive comparison usually doesn't work. And since floating-points -can have a wide value range, no single fixed error bound works. It's better to -compare by a fixed relative error bound, except for values close to 0 due to -the loss of precision there. +Comparing floating-point numbers is tricky. Due to round-off errors, it is very +unlikely that two floating-points will match exactly. Therefore, `ASSERT_EQ` 's +naive comparison usually doesn't work. And since floating-points can have a wide +value range, no single fixed error bound works. It's better to compare by a +fixed relative error bound, except for values close to 0 due to the loss of +precision there. In general, for floating-point comparison to make sense, the user needs to carefully choose the error bound. If they don't want or care to, comparing in -terms of Units in the Last Place (ULPs) is a good default, and Google Test +terms of Units in the Last Place (ULPs) is a good default, and googletest provides assertions to do this. Full details about ULPs are quite long; if you want to learn more, see -[this article on float comparison](https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/). +[here](https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/). -### Floating-Point Macros ### +#### Floating-Point Macros -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_FLOAT_EQ(`_val1, val2_`);` | `EXPECT_FLOAT_EQ(`_val1, val2_`);` | the two `float` values are almost equal | -| `ASSERT_DOUBLE_EQ(`_val1, val2_`);` | `EXPECT_DOUBLE_EQ(`_val1, val2_`);` | the two `double` values are almost equal | +| Fatal assertion | Nonfatal assertion | Verifies | +| ----------------------- | ----------------------- | ----------------------- | +| `ASSERT_FLOAT_EQ(val1, | `EXPECT_FLOAT_EQ(val1, | the two `float` values | +: val2);` : val2);` : are almost equal : +| `ASSERT_DOUBLE_EQ(val1, | `EXPECT_DOUBLE_EQ(val1, | the two `double` values | +: val2);` : val2);` : are almost equal : -By "almost equal", we mean the two values are within 4 ULP's from each -other. +By "almost equal" we mean the values are within 4 ULP's from each other. + +NOTE: `CHECK_DOUBLE_EQ()` in `base/logging.h` uses a fixed absolute error bound, +so its result may differ from that of the googletest macros. That macro is +unsafe and has been deprecated. Please don't use it any more. The following assertions allow you to choose the acceptable error bound: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_NEAR(`_val1, val2, abs\_error_`);` | `EXPECT_NEAR`_(val1, val2, abs\_error_`);` | the difference between _val1_ and _val2_ doesn't exceed the given absolute error | +| Fatal assertion | Nonfatal assertion | Verifies | +| ------------------ | ------------------------ | ------------------------- | +| `ASSERT_NEAR(val1, | `EXPECT_NEAR(val1, val2, | the difference between | +: val2, abs_error);` : abs_error);` : `val1` and `val2` doesn't : +: : : exceed the given absolute : +: : : error : -_Availability_: Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -### Floating-Point Predicate-Format Functions ### +#### Floating-Point Predicate-Format Functions -Some floating-point operations are useful, but not that often used. In order -to avoid an explosion of new macros, we provide them as predicate-format -functions that can be used in predicate assertion macros (e.g. -`EXPECT_PRED_FORMAT2`, etc). +Some floating-point operations are useful, but not that often used. In order to +avoid an explosion of new macros, we provide them as predicate-format functions +that can be used in predicate assertion macros (e.g. `EXPECT_PRED_FORMAT2`, +etc). -``` +```c++ EXPECT_PRED_FORMAT2(::testing::FloatLE, val1, val2); EXPECT_PRED_FORMAT2(::testing::DoubleLE, val1, val2); ``` -Verifies that _val1_ is less than, or almost equal to, _val2_. You can -replace `EXPECT_PRED_FORMAT2` in the above table with `ASSERT_PRED_FORMAT2`. +Verifies that `val1` is less than, or almost equal to, `val2`. You can replace +`EXPECT_PRED_FORMAT2` in the above table with `ASSERT_PRED_FORMAT2`. -_Availability_: Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -## Windows HRESULT assertions ## +### Asserting Using gMock Matchers + +Google-developed C++ mocking framework [gMock](http://go/gmock) comes with a +library of matchers for validating arguments passed to mock objects. A gMock +*matcher* is basically a predicate that knows how to describe itself. It can be +used in these assertion macros: + +| Fatal assertion | Nonfatal assertion | Verifies | +| ------------------- | ------------------------------ | --------------------- | +| `ASSERT_THAT(value, | `EXPECT_THAT(value, matcher);` | value matches matcher | +: matcher);` : : : + +For example, `StartsWith(prefix)` is a matcher that matches a string starting +with `prefix`, and you can write: + +```c++ +using ::testing::StartsWith; +... + // Verifies that Foo() returns a string starting with "Hello". + EXPECT_THAT(Foo(), StartsWith("Hello")); +``` + +Read this [recipe](http://go/gmockguide#using-matchers-in-gunit-assertions) in +the gMock Cookbook for more details. + +gMock has a rich set of matchers. You can do many things googletest cannot do +alone with them. For a list of matchers gMock provides, read +[this](http://go/gmockguide#using-matchers). Especially useful among them are +some [protocol buffer matchers](http://go/protomatchers). It's easy to write +your [own matchers](http://go/gmockguide#NewMatchers) too. + +For example, you can use gMock's +[EqualsProto](http://cs/#piper///depot/google3/testing/base/public/gmock_utils/protocol-buffer-matchers.h) +to compare protos in your tests: + +```c++ +#include "testing/base/public/gmock.h" +using ::testing::EqualsProto; +... + EXPECT_THAT(actual_proto, EqualsProto("foo: 123 bar: 'xyz'")); + EXPECT_THAT(*actual_proto_ptr, EqualsProto(expected_proto)); +``` + +gMock is bundled with googletest, so you don't need to add any build dependency +in order to take advantage of this. Just include `"testing/base/public/gmock.h"` +and you're ready to go. + +**Availability**: Linux, Windows, and Mac. + +### More String Assertions + +(Please read the [previous](#AssertThat) section first if you haven't.) + +You can use the gMock [string matchers](http://go/gmockguide#string-matchers) +with `EXPECT_THAT()` or `ASSERT_THAT()` to do more string comparison tricks +(sub-string, prefix, suffix, regular expression, and etc). For example, + +```c++ +using ::testing::HasSubstr; +using ::testing::MatchesRegex; +... + ASSERT_THAT(foo_string, HasSubstr("needle")); + EXPECT_THAT(bar_string, MatchesRegex("\\w*\\d+")); +``` + +**Availability**: Linux, Windows, Mac. + +If the string contains a well-formed HTML or XML document, you can check whether +its DOM tree matches an [XPath +expression](http://www.w3.org/TR/xpath/#contents): + +```c++ +// Currently still in //template/prototemplate/testing:xpath_matcher +#include "template/prototemplate/testing/xpath_matcher.h" +using prototemplate::testing::MatchesXPath; +EXPECT_THAT(html_string, MatchesXPath("//a[text()='click here']")); +``` + +**Availability**: Linux. + +### Windows HRESULT assertions These assertions test for `HRESULT` success or failure. -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_HRESULT_SUCCEEDED(`_expression_`);` | `EXPECT_HRESULT_SUCCEEDED(`_expression_`);` | _expression_ is a success `HRESULT` | -| `ASSERT_HRESULT_FAILED(`_expression_`);` | `EXPECT_HRESULT_FAILED(`_expression_`);` | _expression_ is a failure `HRESULT` | +Fatal assertion | Nonfatal assertion | Verifies +-------------------------------------- | -------------------------------------- | -------- +`ASSERT_HRESULT_SUCCEEDED(expression)` | `EXPECT_HRESULT_SUCCEEDED(expression)` | `expression` is a success `HRESULT` +`ASSERT_HRESULT_FAILED(expression)` | `EXPECT_HRESULT_FAILED(expression)` | `expression` is a failure `HRESULT` -The generated output contains the human-readable error message -associated with the `HRESULT` code returned by _expression_. +The generated output contains the human-readable error message associated with +the `HRESULT` code returned by `expression`. You might use them like this: -``` -CComPtr shell; +```c++ +CComPtr shell; ASSERT_HRESULT_SUCCEEDED(shell.CoCreateInstance(L"Shell.Application")); CComVariant empty; ASSERT_HRESULT_SUCCEEDED(shell->ShellExecute(CComBSTR(url), empty, empty, empty, empty)); ``` -_Availability_: Windows. +**Availability**: Windows. -## Type Assertions ## +### Type Assertions You can call the function -``` + +```c++ ::testing::StaticAssertTypeEq(); ``` -to assert that types `T1` and `T2` are the same. The function does -nothing if the assertion is satisfied. If the types are different, -the function call will fail to compile, and the compiler error message -will likely (depending on the compiler) show you the actual values of -`T1` and `T2`. This is mainly useful inside template code. -_Caveat:_ When used inside a member function of a class template or a -function template, `StaticAssertTypeEq()` is effective _only if_ -the function is instantiated. For example, given: -``` +to assert that types `T1` and `T2` are the same. The function does nothing if +the assertion is satisfied. If the types are different, the function call will +fail to compile, and the compiler error message will likely (depending on the +compiler) show you the actual values of `T1` and `T2`. This is mainly useful +inside template code. + +**Caveat**: When used inside a member function of a class template or a function +template, `StaticAssertTypeEq()` is effective only if the function is +instantiated. For example, given: + +```c++ template class Foo { public: void Bar() { ::testing::StaticAssertTypeEq(); } }; ``` + the code: -``` + +```c++ void Test1() { Foo foo; } ``` -will _not_ generate a compiler error, as `Foo::Bar()` is never -actually instantiated. Instead, you need: -``` + +will not generate a compiler error, as `Foo::Bar()` is never actually +instantiated. Instead, you need: + +```c++ void Test2() { Foo foo; foo.Bar(); } ``` + to cause a compiler error. -_Availability:_ Linux, Windows, Mac; since version 1.3.0. +**Availability**: Linux, Windows, Mac. -## Assertion Placement ## +### Assertion Placement -You can use assertions in any C++ function. In particular, it doesn't -have to be a method of the test fixture class. The one constraint is -that assertions that generate a fatal failure (`FAIL*` and `ASSERT_*`) -can only be used in void-returning functions. This is a consequence of -Google Test not using exceptions. By placing it in a non-void function -you'll get a confusing compile error like -`"error: void value not ignored as it ought to be"`. +You can use assertions in any C++ function. In particular, it doesn't have to be +a method of the test fixture class. The one constraint is that assertions that +generate a fatal failure (`FAIL*` and `ASSERT_*`) can only be used in +void-returning functions. This is a consequence of Google's not using +exceptions. By placing it in a non-void function you'll get a confusing compile +error like `"error: void value not ignored as it ought to be"` or `"cannot +initialize return object of type 'bool' with an rvalue of type 'void'"` or +`"error: no viable conversion from 'void' to 'string'"`. -If you need to use assertions in a function that returns non-void, one option -is to make the function return the value in an out parameter instead. For +If you need to use fatal assertions in a function that returns non-void, one +option is to make the function return the value in an out parameter instead. For example, you can rewrite `T2 Foo(T1 x)` to `void Foo(T1 x, T2* result)`. You need to make sure that `*result` contains some sensible value even when the function returns prematurely. As the function now returns `void`, you can use any assertion inside of it. -If changing the function's type is not an option, you should just use -assertions that generate non-fatal failures, such as `ADD_FAILURE*` and -`EXPECT_*`. +If changing the function's type is not an option, you should just use assertions +that generate non-fatal failures, such as `ADD_FAILURE*` and `EXPECT_*`. -_Note_: Constructors and destructors are not considered void-returning -functions, according to the C++ language specification, and so you may not use -fatal assertions in them. You'll get a compilation error if you try. A simple +NOTE: Constructors and destructors are not considered void-returning functions, +according to the C++ language specification, and so you may not use fatal +assertions in them. You'll get a compilation error if you try. A simple workaround is to transfer the entire body of the constructor or destructor to a private void-returning method. However, you should be aware that a fatal assertion failure in a constructor does not terminate the current test, as your @@ -432,30 +557,37 @@ leaving your object in a partially-constructed state. Likewise, a fatal assertion failure in a destructor may leave your object in a partially-destructed state. Use assertions carefully in these situations! -# Teaching Google Test How to Print Your Values # +## Teaching googletest How to Print Your Values -When a test assertion such as `EXPECT_EQ` fails, Google Test prints the -argument values to help you debug. It does this using a -user-extensible value printer. +When a test assertion such as `EXPECT_EQ` fails, googletest prints the argument +values to help you debug. It does this using a user-extensible value printer. This printer knows how to print built-in C++ types, native arrays, STL -containers, and any type that supports the `<<` operator. For other -types, it prints the raw bytes in the value and hopes that you the -user can figure it out. +containers, and any type that supports the `<<` operator. For other types, it +prints the raw bytes in the value and hopes that you the user can figure it out. -As mentioned earlier, the printer is _extensible_. That means -you can teach it to do a better job at printing your particular type -than to dump the bytes. To do that, define `<<` for your type: +As mentioned earlier, the printer is *extensible*. That means you can teach it +to do a better job at printing your particular type than to dump the bytes. To +do that, define `<<` for your type: -``` -#include +```c++ +// Streams are allowed only for logging. Don't include this for +// any other purpose. +#include namespace foo { -class Bar { ... }; // We want Google Test to be able to print instances of this. +class Bar { // We want googletest to be able to print instances of this. +... + // Create a free inline friend function. + friend ::std::ostream& operator<<(::std::ostream& os, const Bar& bar) { + return os << bar.DebugString(); // whatever needed to print bar to os + } +}; -// It's important that the << operator is defined in the SAME -// namespace that defines Bar. C++'s look-up rules rely on that. +// If you can't declare the function in the class it's important that the +// << operator is defined in the SAME namespace that defines Bar. C++'s look-up +// rules rely on that. ::std::ostream& operator<<(::std::ostream& os, const Bar& bar) { return os << bar.DebugString(); // whatever needed to print bar to os } @@ -463,20 +595,28 @@ class Bar { ... }; // We want Google Test to be able to print instances of this } // namespace foo ``` -Sometimes, this might not be an option: your team may consider it bad -style to have a `<<` operator for `Bar`, or `Bar` may already have a -`<<` operator that doesn't do what you want (and you cannot change -it). If so, you can instead define a `PrintTo()` function like this: +Sometimes, this might not be an option: your team may consider it bad style to +have a `<<` operator for `Bar`, or `Bar` may already have a `<<` operator that +doesn't do what you want (and you cannot change it). If so, you can instead +define a `PrintTo()` function like this: -``` -#include +```c++ +// Streams are allowed only for logging. Don't include this for +// any other purpose. +#include namespace foo { -class Bar { ... }; +class Bar { + ... + friend void PrintTo(const Bar& bar, ::std::ostream* os) { + *os << bar.DebugString(); // whatever needed to print bar to os + } +}; -// It's important that PrintTo() is defined in the SAME -// namespace that defines Bar. C++'s look-up rules rely on that. +// If you can't declare the function in the class it's important that PrintTo() +// is defined in the SAME namespace that defines Bar. C++'s look-up rules rely +// on that. void PrintTo(const Bar& bar, ::std::ostream* os) { *os << bar.DebugString(); // whatever needed to print bar to os } @@ -484,85 +624,86 @@ void PrintTo(const Bar& bar, ::std::ostream* os) { } // namespace foo ``` -If you have defined both `<<` and `PrintTo()`, the latter will be used -when Google Test is concerned. This allows you to customize how the value -appears in Google Test's output without affecting code that relies on the -behavior of its `<<` operator. +If you have defined both `<<` and `PrintTo()`, the latter will be used when +googletest is concerned. This allows you to customize how the value appears in +googletest's output without affecting code that relies on the behavior of its +`<<` operator. -If you want to print a value `x` using Google Test's value printer -yourself, just call `::testing::PrintToString(`_x_`)`, which -returns an `std::string`: +If you want to print a value `x` using googletest's value printer yourself, just +call `::testing::PrintToString(x)`, which returns an `std::string`: -``` +```c++ vector > bar_ints = GetBarIntVector(); EXPECT_TRUE(IsCorrectBarIntVector(bar_ints)) << "bar_ints = " << ::testing::PrintToString(bar_ints); ``` -# Death Tests # +## Death Tests -In many applications, there are assertions that can cause application failure -if a condition is not met. These sanity checks, which ensure that the program -is in a known good state, are there to fail at the earliest possible time after -some program state is corrupted. If the assertion checks the wrong condition, -then the program may proceed in an erroneous state, which could lead to memory -corruption, security holes, or worse. Hence it is vitally important to test -that such assertion statements work as expected. +In many applications, there are assertions that can cause application failure if +a condition is not met. These sanity checks, which ensure that the program is in +a known good state, are there to fail at the earliest possible time after some +program state is corrupted. If the assertion checks the wrong condition, then +the program may proceed in an erroneous state, which could lead to memory +corruption, security holes, or worse. Hence it is vitally important to test that +such assertion statements work as expected. Since these precondition checks cause the processes to die, we call such tests _death tests_. More generally, any test that checks that a program terminates (except by throwing an exception) in an expected fashion is also a death test. + Note that if a piece of code throws an exception, we don't consider it "death" -for the purpose of death tests, as the caller of the code could catch the exception -and avoid the crash. If you want to verify exceptions thrown by your code, -see [Exception Assertions](#exception-assertions). +for the purpose of death tests, as the caller of the code could catch the +exception and avoid the crash. If you want to verify exceptions thrown by your +code, see [Exception Assertions](#ExceptionAssertions). -If you want to test `EXPECT_*()/ASSERT_*()` failures in your test code, see [Catching Failures](#catching-failures). +If you want to test `EXPECT_*()/ASSERT_*()` failures in your test code, see +Catching Failures -## How to Write a Death Test ## +### How to Write a Death Test -Google Test has the following macros to support death tests: +googletest has the following macros to support death tests: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_DEATH(`_statement, regex_`);` | `EXPECT_DEATH(`_statement, regex_`);` | _statement_ crashes with the given error | -| `ASSERT_DEATH_IF_SUPPORTED(`_statement, regex_`);` | `EXPECT_DEATH_IF_SUPPORTED(`_statement, regex_`);` | if death tests are supported, verifies that _statement_ crashes with the given error; otherwise verifies nothing | -| `ASSERT_EXIT(`_statement, predicate, regex_`);` | `EXPECT_EXIT(`_statement, predicate, regex_`);` |_statement_ exits with the given error and its exit code matches _predicate_ | +Fatal assertion | Nonfatal assertion | Verifies +---------------------------------------------- | ---------------------------------------------- | -------- +`ASSERT_DEATH(statement, regex);` | `EXPECT_DEATH(statement, regex);` | `statement` crashes with the given error +`ASSERT_DEATH_IF_SUPPORTED(statement, regex);` | `EXPECT_DEATH_IF_SUPPORTED(statement, regex);` | if death tests are supported, verifies that `statement` crashes with the given error; otherwise verifies nothing +`ASSERT_EXIT(statement, predicate, regex);` | `EXPECT_EXIT(statement, predicate, regex);` | `statement` exits with the given error, and its exit code matches `predicate` -where _statement_ is a statement that is expected to cause the process to -die, _predicate_ is a function or function object that evaluates an integer -exit status, and _regex_ is a regular expression that the stderr output of -_statement_ is expected to match. Note that _statement_ can be _any valid -statement_ (including _compound statement_) and doesn't have to be an +where `statement` is a statement that is expected to cause the process to die, +`predicate` is a function or function object that evaluates an integer exit +status, and `regex` is a (Perl) regular expression that the stderr output of +`statement` is expected to match. Note that `statement` can be *any valid +statement* (including *compound statement*) and doesn't have to be an expression. + As usual, the `ASSERT` variants abort the current test function, while the `EXPECT` variants do not. -**Note:** We use the word "crash" here to mean that the process -terminates with a _non-zero_ exit status code. There are two -possibilities: either the process has called `exit()` or `_exit()` -with a non-zero value, or it may be killed by a signal. - -This means that if _statement_ terminates the process with a 0 exit -code, it is _not_ considered a crash by `EXPECT_DEATH`. Use -`EXPECT_EXIT` instead if this is the case, or if you want to restrict -the exit code more precisely. +> NOTE: We use the word "crash" here to mean that the process terminates with a +> *non-zero* exit status code. There are two possibilities: either the process +> has called `exit()` or `_exit()` with a non-zero value, or it may be killed by +> a signal. +> +> This means that if `*statement*` terminates the process with a 0 exit code, it +> is *not* considered a crash by `EXPECT_DEATH`. Use `EXPECT_EXIT` instead if +> this is the case, or if you want to restrict the exit code more precisely. A predicate here must accept an `int` and return a `bool`. The death test -succeeds only if the predicate returns `true`. Google Test defines a few +succeeds only if the predicate returns `true`. googletest defines a few predicates that handle the most common cases: -``` +```c++ ::testing::ExitedWithCode(exit_code) ``` This expression is `true` if the program exited normally with the given exit code. -``` +```c++ ::testing::KilledBySignal(signal_number) // Not available on Windows. ``` @@ -573,49 +714,63 @@ that verifies the process' exit code is non-zero. Note that a death test only cares about three things: - 1. does _statement_ abort or exit the process? - 1. (in the case of `ASSERT_EXIT` and `EXPECT_EXIT`) does the exit status satisfy _predicate_? Or (in the case of `ASSERT_DEATH` and `EXPECT_DEATH`) is the exit status non-zero? And - 1. does the stderr output match _regex_? +1. does `statement` abort or exit the process? +2. (in the case of `ASSERT_EXIT` and `EXPECT_EXIT`) does the exit status + satisfy `predicate`? Or (in the case of `ASSERT_DEATH` and `EXPECT_DEATH`) + is the exit status non-zero? And +3. does the stderr output match `regex`? -In particular, if _statement_ generates an `ASSERT_*` or `EXPECT_*` failure, it will **not** cause the death test to fail, as Google Test assertions don't abort the process. +In particular, if `statement` generates an `ASSERT_*` or `EXPECT_*` failure, it +will **not** cause the death test to fail, as googletest assertions don't abort +the process. To write a death test, simply use one of the above macros inside your test function. For example, -``` +```c++ TEST(MyDeathTest, Foo) { // This death test uses a compound statement. - ASSERT_DEATH({ int n = 5; Foo(&n); }, "Error on line .* of Foo()"); + ASSERT_DEATH({ + int n = 5; + Foo(&n); + }, "Error on line .* of Foo()"); } + TEST(MyDeathTest, NormalExit) { EXPECT_EXIT(NormalExit(), ::testing::ExitedWithCode(0), "Success"); } + TEST(MyDeathTest, KillMyself) { - EXPECT_EXIT(KillMyself(), ::testing::KilledBySignal(SIGKILL), "Sending myself unblockable signal"); + EXPECT_EXIT(KillMyself(), ::testing::KilledBySignal(SIGKILL), + "Sending myself unblockable signal"); } ``` verifies that: - * calling `Foo(5)` causes the process to die with the given error message, - * calling `NormalExit()` causes the process to print `"Success"` to stderr and exit with exit code 0, and - * calling `KillMyself()` kills the process with signal `SIGKILL`. +* calling `Foo(5)` causes the process to die with the given error message, +* calling `NormalExit()` causes the process to print `"Success"` to stderr and + exit with exit code 0, and +* calling `KillMyself()` kills the process with signal `SIGKILL`. The test function body may contain other assertions and statements as well, if necessary. -_Important:_ We strongly recommend you to follow the convention of naming your -test case (not test) `*DeathTest` when it contains a death test, as -demonstrated in the above example. The `Death Tests And Threads` section below -explains why. +### Death Test Naming -If a test fixture class is shared by normal tests and death tests, you -can use typedef to introduce an alias for the fixture class and avoid +IMPORTANT: We strongly recommend you to follow the convention of naming your +**test case** (not test) `*DeathTest` when it contains a death test, as +demonstrated in the above example. The [Death Tests And +Threads](#death-tests-and-threads) section below explains why. + +If a test fixture class is shared by normal tests and death tests, you can use +`using` or `typedef` to introduce an alias for the fixture class and avoid duplicating its code: -``` + +```c++ class FooTest : public ::testing::Test { ... }; -typedef FooTest FooDeathTest; +using FooDeathTest = FooTest; TEST_F(FooTest, DoesThis) { // normal test @@ -626,79 +781,86 @@ TEST_F(FooDeathTest, DoesThat) { } ``` -_Availability:_ Linux, Windows (requires MSVC 8.0 or above), Cygwin, and Mac (the latter three are supported since v1.3.0). `(ASSERT|EXPECT)_DEATH_IF_SUPPORTED` are new in v1.4.0. +**Availability**: Linux, Windows (requires MSVC 8.0 or above), Cygwin, and Mac -## Regular Expression Syntax ## +### Regular Expression Syntax -On POSIX systems (e.g. Linux, Cygwin, and Mac), Google Test uses the + +On POSIX systems (e.g. Linux, Cygwin, and Mac), googletest uses the [POSIX extended regular expression](http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_04) -syntax in death tests. To learn about this syntax, you may want to read this [Wikipedia entry](http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions). +syntax. To learn about this syntax, you may want to read this +[Wikipedia entry](http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions). -On Windows, Google Test uses its own simple regular expression -implementation. It lacks many features you can find in POSIX extended -regular expressions. For example, we don't support union (`"x|y"`), -grouping (`"(xy)"`), brackets (`"[xy]"`), and repetition count -(`"x{5,7}"`), among others. Below is what we do support (Letter `A` denotes a -literal character, period (`.`), or a single `\\` escape sequence; `x` -and `y` denote regular expressions.): +On Windows, googletest uses its own simple regular expression implementation. It +lacks many features. For example, we don't support union (`"x|y"`), grouping +(`"(xy)"`), brackets (`"[xy]"`), and repetition count (`"x{5,7}"`), among +others. Below is what we do support (`A` denotes a literal character, period +(`.`), or a single `\\ ` escape sequence; `x` and `y` denote regular +expressions.): -| `c` | matches any literal character `c` | -|:----|:----------------------------------| -| `\\d` | matches any decimal digit | -| `\\D` | matches any character that's not a decimal digit | -| `\\f` | matches `\f` | -| `\\n` | matches `\n` | -| `\\r` | matches `\r` | -| `\\s` | matches any ASCII whitespace, including `\n` | -| `\\S` | matches any character that's not a whitespace | -| `\\t` | matches `\t` | -| `\\v` | matches `\v` | -| `\\w` | matches any letter, `_`, or decimal digit | -| `\\W` | matches any character that `\\w` doesn't match | -| `\\c` | matches any literal character `c`, which must be a punctuation | -| `\\.` | matches the `.` character | -| `.` | matches any single character except `\n` | -| `A?` | matches 0 or 1 occurrences of `A` | -| `A*` | matches 0 or many occurrences of `A` | -| `A+` | matches 1 or many occurrences of `A` | -| `^` | matches the beginning of a string (not that of each line) | -| `$` | matches the end of a string (not that of each line) | -| `xy` | matches `x` followed by `y` | +Expression | Meaning +---------- | -------------------------------------------------------------- +`c` | matches any literal character `c` +`\\d` | matches any decimal digit +`\\D` | matches any character that's not a decimal digit +`\\f` | matches `\f` +`\\n` | matches `\n` +`\\r` | matches `\r` +`\\s` | matches any ASCII whitespace, including `\n` +`\\S` | matches any character that's not a whitespace +`\\t` | matches `\t` +`\\v` | matches `\v` +`\\w` | matches any letter, `_`, or decimal digit +`\\W` | matches any character that `\\w` doesn't match +`\\c` | matches any literal character `c`, which must be a punctuation +`.` | matches any single character except `\n` +`A?` | matches 0 or 1 occurrences of `A` +`A*` | matches 0 or many occurrences of `A` +`A+` | matches 1 or many occurrences of `A` +`^` | matches the beginning of a string (not that of each line) +`$` | matches the end of a string (not that of each line) +`xy` | matches `x` followed by `y` -To help you determine which capability is available on your system, -Google Test defines macro `GTEST_USES_POSIX_RE=1` when it uses POSIX -extended regular expressions, or `GTEST_USES_SIMPLE_RE=1` when it uses -the simple version. If you want your death tests to work in both -cases, you can either `#if` on these macros or use the more limited -syntax only. +To help you determine which capability is available on your system, googletest +defines macros to govern which regular expression it is using. The macros are: +`GTEST_USES_PCRE=1`, or + `GTEST_USES_SIMPLE_RE=1` or `GTEST_USES_POSIX_RE=1`. If +you want your death tests to work in all cases, you can either `#if` on these +macros or use the more limited syntax only. -## How It Works ## +### How It Works -Under the hood, `ASSERT_EXIT()` spawns a new process and executes the -death test statement in that process. The details of how precisely -that happens depend on the platform and the variable -`::testing::GTEST_FLAG(death_test_style)` (which is initialized from the -command-line flag `--gtest_death_test_style`). +Under the hood, `ASSERT_EXIT()` spawns a new process and executes the death test +statement in that process. The details of how precisely that happens depend on +the platform and the variable ::testing::GTEST_FLAG(death_test_style) (which is +initialized from the command-line flag `--gtest_death_test_style`). - * On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the child, after which: - * If the variable's value is `"fast"`, the death test statement is immediately executed. - * If the variable's value is `"threadsafe"`, the child process re-executes the unit test binary just as it was originally invoked, but with some extra flags to cause just the single death test under consideration to be run. - * On Windows, the child is spawned using the `CreateProcess()` API, and re-executes the binary to cause just the single death test under consideration to be run - much like the `threadsafe` mode on POSIX. +* On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the + child, after which: + * If the variable's value is `"fast"`, the death test statement is + immediately executed. + * If the variable's value is `"threadsafe"`, the child process re-executes + the unit test binary just as it was originally invoked, but with some + extra flags to cause just the single death test under consideration to + be run. +* On Windows, the child is spawned using the `CreateProcess()` API, and + re-executes the binary to cause just the single death test under + consideration to be run - much like the `threadsafe` mode on POSIX. -Other values for the variable are illegal and will cause the death test to -fail. Currently, the flag's default value is `"fast"`. However, we reserve the -right to change it in the future. Therefore, your tests should not depend on -this. +Other values for the variable are illegal and will cause the death test to fail. +Currently, the flag's default value is +"fast". However, we reserve +the right to change it in the future. Therefore, your tests should not depend on +this. In either case, the parent process waits for the child process to +complete, and checks that -In either case, the parent process waits for the child process to complete, and checks that +1. the child's exit status satisfies the predicate, and +2. the child's stderr matches the regular expression. - 1. the child's exit status satisfies the predicate, and - 1. the child's stderr matches the regular expression. +If the death test statement runs to completion without dying, the child process +will nonetheless terminate, and the assertion fails. -If the death test statement runs to completion without dying, the child -process will nonetheless terminate, and the assertion fails. - -## Death Tests And Threads ## +### Death Tests And Threads The reason for the two death test styles has to do with thread safety. Due to well-known problems with forking in the presence of threads, death tests should @@ -707,35 +869,43 @@ arrange that kind of environment. For example, statically-initialized modules may start threads before main is ever reached. Once threads have been created, it may be difficult or impossible to clean them up. -Google Test has three features intended to raise awareness of threading issues. +googletest has three features intended to raise awareness of threading issues. - 1. A warning is emitted if multiple threads are running when a death test is encountered. - 1. Test cases with a name ending in "DeathTest" are run before all other tests. - 1. It uses `clone()` instead of `fork()` to spawn the child process on Linux (`clone()` is not available on Cygwin and Mac), as `fork()` is more likely to cause the child to hang when the parent process has multiple threads. +1. A warning is emitted if multiple threads are running when a death test is + encountered. +2. Test cases with a name ending in "DeathTest" are run before all other tests. +3. It uses `clone()` instead of `fork()` to spawn the child process on Linux + (`clone()` is not available on Cygwin and Mac), as `fork()` is more likely + to cause the child to hang when the parent process has multiple threads. It's perfectly fine to create threads inside a death test statement; they are executed in a separate process and cannot affect the parent. -## Death Test Styles ## +### Death Test Styles + The "threadsafe" death test style was introduced in order to help mitigate the risks of testing in a possibly multithreaded environment. It trades increased test execution time (potentially dramatically so) for improved thread safety. -We suggest using the faster, default "fast" style unless your test has specific -problems with it. -You can choose a particular style of death tests by setting the flag -programmatically: +The automated testing framework does not set the style flag. You can choose a +particular style of death tests by setting the flag programmatically: -``` -::testing::FLAGS_gtest_death_test_style = "threadsafe"; +```c++ +testing::FLAGS_gtest_death_test_style="threadsafe" ``` -You can do this in `main()` to set the style for all death tests in the -binary, or in individual tests. Recall that flags are saved before running each -test and restored afterwards, so you need not do that yourself. For example: +You can do this in `main()` to set the style for all death tests in the binary, +or in individual tests. Recall that flags are saved before running each test and +restored afterwards, so you need not do that yourself. For example: + +```c++ +int main(int argc, char** argv) { + InitGoogle(argv[0], &argc, &argv, true); + ::testing::FLAGS_gtest_death_test_style = "fast"; + return RUN_ALL_TESTS(); +} -``` TEST(MyDeathTest, TestOne) { ::testing::FLAGS_gtest_death_test_style = "threadsafe"; // This test is run in the "threadsafe" style: @@ -746,52 +916,51 @@ TEST(MyDeathTest, TestTwo) { // This test is run in the "fast" style: ASSERT_DEATH(ThisShouldDie(), ""); } - -int main(int argc, char** argv) { - ::testing::InitGoogleTest(&argc, argv); - ::testing::FLAGS_gtest_death_test_style = "fast"; - return RUN_ALL_TESTS(); -} ``` -## Caveats ## -The _statement_ argument of `ASSERT_EXIT()` can be any valid C++ statement. -If it leaves the current function via a `return` statement or by throwing an exception, -the death test is considered to have failed. Some Google Test macros may return -from the current function (e.g. `ASSERT_TRUE()`), so be sure to avoid them in _statement_. +### Caveats -Since _statement_ runs in the child process, any in-memory side effect (e.g. -modifying a variable, releasing memory, etc) it causes will _not_ be observable +The `statement` argument of `ASSERT_EXIT()` can be any valid C++ statement. If +it leaves the current function via a `return` statement or by throwing an +exception, the death test is considered to have failed. Some googletest macros +may return from the current function (e.g. `ASSERT_TRUE()`), so be sure to avoid +them in `statement`. + +Since `statement` runs in the child process, any in-memory side effect (e.g. +modifying a variable, releasing memory, etc) it causes will *not* be observable in the parent process. In particular, if you release memory in a death test, your program will fail the heap check as the parent process will never see the memory reclaimed. To solve this problem, you can - 1. try not to free memory in a death test; - 1. free the memory again in the parent process; or - 1. do not use the heap checker in your program. +1. try not to free memory in a death test; +2. free the memory again in the parent process; or +3. do not use the heap checker in your program. -Due to an implementation detail, you cannot place multiple death test -assertions on the same line; otherwise, compilation will fail with an unobvious -error message. +Due to an implementation detail, you cannot place multiple death test assertions +on the same line; otherwise, compilation will fail with an unobvious error +message. Despite the improved thread safety afforded by the "threadsafe" style of death test, thread problems such as deadlock are still possible in the presence of handlers registered with `pthread_atfork(3)`. -# Using Assertions in Sub-routines # -## Adding Traces to Assertions ## +## Using Assertions in Sub-routines -If a test sub-routine is called from several places, when an assertion -inside it fails, it can be hard to tell which invocation of the -sub-routine the failure is from. You can alleviate this problem using -extra logging or custom failure messages, but that usually clutters up -your tests. A better solution is to use the `SCOPED_TRACE` macro or -the `ScopedTrace` utility: +### Adding Traces to Assertions -| `SCOPED_TRACE(`_message_`);` | `::testing::ScopedTrace trace(`_"file\_path"_`, `_line\_number_`, `_message_`);` | -|:-----------------------------|:---------------------------------------------------------------------------------| +If a test sub-routine is called from several places, when an assertion inside it +fails, it can be hard to tell which invocation of the sub-routine the failure is +from. +You can alleviate this problem using extra logging or custom failure messages, +but that usually clutters up your tests. A better solution is to use the +`SCOPED_TRACE` macro or the `ScopedTrace` utility: + +```c++ +SCOPED_TRACE(message); +ScopedTrace trace("file_path", line_number, message); +``` where `message` can be anything streamable to `std::ostream`. `SCOPED_TRACE` macro will cause the current file name, line number, and the given message to be @@ -801,7 +970,7 @@ will be undone when the control leaves the current lexical scope. For example, -``` +```c++ 10: void Sub1(int n) { 11: EXPECT_EQ(1, Bar(n)); 12: EXPECT_EQ(2, Bar(n + 1)); @@ -820,7 +989,7 @@ For example, could result in messages like these: -``` +```none path/to/foo_test.cc:11: Failure Value of: Bar(n) Expected: 1 @@ -834,45 +1003,56 @@ Expected: 2 Actual: 3 ``` -Without the trace, it would've been difficult to know which invocation -of `Sub1()` the two failures come from respectively. (You could add an -extra message to each assertion in `Sub1()` to indicate the value of -`n`, but that's tedious.) +Without the trace, it would've been difficult to know which invocation of +`Sub1()` the two failures come from respectively. (You could add + +an extra message to each assertion in `Sub1()` to indicate the value of `n`, but +that's tedious.) Some tips on using `SCOPED_TRACE`: - 1. With a suitable message, it's often enough to use `SCOPED_TRACE` at the beginning of a sub-routine, instead of at each call site. - 1. When calling sub-routines inside a loop, make the loop iterator part of the message in `SCOPED_TRACE` such that you can know which iteration the failure is from. - 1. Sometimes the line number of the trace point is enough for identifying the particular invocation of a sub-routine. In this case, you don't have to choose a unique message for `SCOPED_TRACE`. You can simply use `""`. - 1. You can use `SCOPED_TRACE` in an inner scope when there is one in the outer scope. In this case, all active trace points will be included in the failure messages, in reverse order they are encountered. - 1. The trace dump is clickable in Emacs' compilation buffer - hit return on a line number and you'll be taken to that line in the source file! +1. With a suitable message, it's often enough to use `SCOPED_TRACE` at the + beginning of a sub-routine, instead of at each call site. +2. When calling sub-routines inside a loop, make the loop iterator part of the + message in `SCOPED_TRACE` such that you can know which iteration the failure + is from. +3. Sometimes the line number of the trace point is enough for identifying the + particular invocation of a sub-routine. In this case, you don't have to + choose a unique message for `SCOPED_TRACE`. You can simply use `""`. +4. You can use `SCOPED_TRACE` in an inner scope when there is one in the outer + scope. In this case, all active trace points will be included in the failure + messages, in reverse order they are encountered. +5. The trace dump is clickable in Emacs - hit `return` on a line number and + you'll be taken to that line in the source file! -_Availability:_ Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -## Propagating Fatal Failures ## +### Propagating Fatal Failures A common pitfall when using `ASSERT_*` and `FAIL*` is not understanding that when they fail they only abort the _current function_, not the entire test. For example, the following test will segfault: -``` + +```c++ void Subroutine() { // Generates a fatal failure and aborts the current function. ASSERT_EQ(1, 2); + // The following won't be executed. ... } TEST(FooTest, Bar) { - Subroutine(); - // The intended behavior is for the fatal failure - // in Subroutine() to abort the entire test. + Subroutine(); // The intended behavior is for the fatal failure + // in Subroutine() to abort the entire test. + // The actual behavior: the function goes on after Subroutine() returns. int* p = NULL; - *p = 3; // Segfault! + *p = 3; // Segfault! } ``` -To alleviate this, gUnit provides three different solutions. You could use +To alleviate this, googletest provides three different solutions. You could use either exceptions, the `(ASSERT|EXPECT)_NO_FATAL_FAILURE` assertions or the `HasFatalFailure()` function. They are described in the following two subsections. @@ -899,26 +1079,26 @@ int main(int argc, char** argv) { This listener should be added after other listeners if you have any, otherwise they won't see failed `OnTestPartResult`. -### Asserting on Subroutines ### +#### Asserting on Subroutines -As shown above, if your test calls a subroutine that has an `ASSERT_*` -failure in it, the test will continue after the subroutine -returns. This may not be what you want. +As shown above, if your test calls a subroutine that has an `ASSERT_*` failure +in it, the test will continue after the subroutine returns. This may not be what +you want. -Often people want fatal failures to propagate like exceptions. For -that Google Test offers the following macros: +Often people want fatal failures to propagate like exceptions. For that +googletest offers the following macros: -| **Fatal assertion** | **Nonfatal assertion** | **Verifies** | -|:--------------------|:-----------------------|:-------------| -| `ASSERT_NO_FATAL_FAILURE(`_statement_`);` | `EXPECT_NO_FATAL_FAILURE(`_statement_`);` | _statement_ doesn't generate any new fatal failures in the current thread. | +Fatal assertion | Nonfatal assertion | Verifies +------------------------------------- | ------------------------------------- | -------- +`ASSERT_NO_FATAL_FAILURE(statement);` | `EXPECT_NO_FATAL_FAILURE(statement);` | `statement` doesn't generate any new fatal failures in the current thread. -Only failures in the thread that executes the assertion are checked to -determine the result of this type of assertions. If _statement_ -creates new threads, failures in these threads are ignored. +Only failures in the thread that executes the assertion are checked to determine +the result of this type of assertions. If `statement` creates new threads, +failures in these threads are ignored. Examples: -``` +```c++ ASSERT_NO_FATAL_FAILURE(Foo()); int i; @@ -927,17 +1107,16 @@ EXPECT_NO_FATAL_FAILURE({ }); ``` -_Availability:_ Linux, Windows, Mac. Assertions from multiple threads -are currently not supported. +**Availability**: Linux, Windows, Mac. Assertions from multiple threads are +currently not supported on Windows. -### Checking for Failures in the Current Test ### +#### Checking for Failures in the Current Test `HasFatalFailure()` in the `::testing::Test` class returns `true` if an -assertion in the current test has suffered a fatal failure. This -allows functions to catch fatal failures in a sub-routine and return -early. +assertion in the current test has suffered a fatal failure. This allows +functions to catch fatal failures in a sub-routine and return early. -``` +```c++ class Test { public: ... @@ -945,15 +1124,15 @@ class Test { }; ``` -The typical usage, which basically simulates the behavior of a thrown -exception, is: +The typical usage, which basically simulates the behavior of a thrown exception, +is: -``` +```c++ TEST(FooTest, Bar) { Subroutine(); // Aborts if Subroutine() had a fatal failure. - if (HasFatalFailure()) - return; + if (HasFatalFailure()) return; + // The following won't be executed. ... } @@ -962,25 +1141,24 @@ TEST(FooTest, Bar) { If `HasFatalFailure()` is used outside of `TEST()` , `TEST_F()` , or a test fixture, you must add the `::testing::Test::` prefix, as in: -``` -if (::testing::Test::HasFatalFailure()) - return; +```c++ +if (::testing::Test::HasFatalFailure()) return; ``` -Similarly, `HasNonfatalFailure()` returns `true` if the current test -has at least one non-fatal failure, and `HasFailure()` returns `true` -if the current test has at least one failure of either kind. +Similarly, `HasNonfatalFailure()` returns `true` if the current test has at +least one non-fatal failure, and `HasFailure()` returns `true` if the current +test has at least one failure of either kind. -_Availability:_ Linux, Windows, Mac. `HasNonfatalFailure()` and -`HasFailure()` are available since version 1.4.0. +**Availability**: Linux, Windows, Mac. -# Logging Additional Information # +## Logging Additional Information -In your test code, you can call `RecordProperty("key", value)` to log -additional information, where `value` can be either a string or an `int`. The _last_ value recorded for a key will be emitted to the XML output -if you specify one. For example, the test +In your test code, you can call `RecordProperty("key", value)` to log additional +information, where `value` can be either a string or an `int`. The *last* value +recorded for a key will be emitted to the [XML output](#XmlReport) if you +specify one. For example, the test -``` +```c++ TEST_F(WidgetUsageTest, MinAndMaxWidgets) { RecordProperty("MaximumWidgets", ComputeMaxUsage()); RecordProperty("MinimumWidgets", ComputeMinUsage()); @@ -989,51 +1167,63 @@ TEST_F(WidgetUsageTest, MinAndMaxWidgets) { will output XML like this: -``` -... - -... +```xml + ... + + ... ``` -_Note_: - * `RecordProperty()` is a static member of the `Test` class. Therefore it needs to be prefixed with `::testing::Test::` if used outside of the `TEST` body and the test fixture class. - * `key` must be a valid XML attribute name, and cannot conflict with the ones already used by Google Test (`name`, `status`, `time`, `classname`, `type_param`, and `value_param`). - * Calling `RecordProperty()` outside of the lifespan of a test is allowed. If it's called outside of a test but between a test case's `SetUpTestCase()` and `TearDownTestCase()` methods, it will be attributed to the XML element for the test case. If it's called outside of all test cases (e.g. in a test environment), it will be attributed to the top-level XML element. +> NOTE: +> +> * `RecordProperty()` is a static member of the `Test` class. Therefore it +> needs to be prefixed with `::testing::Test::` if used outside of the +> `TEST` body and the test fixture class. +> * `*key*` must be a valid XML attribute name, and cannot conflict with the +> ones already used by googletest (`name`, `status`, `time`, `classname`, +> `type_param`, and `value_param`). +> * Calling `RecordProperty()` outside of the lifespan of a test is allowed. +> If it's called outside of a test but between a test case's +> `SetUpTestCase()` and `TearDownTestCase()` methods, it will be attributed +> to the XML element for the test case. If it's called outside of all test +> cases (e.g. in a test environment), it will be attributed to the top-level +> XML element. -_Availability_: Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -# Sharing Resources Between Tests in the Same Test Case # +## Sharing Resources Between Tests in the Same Test Case - - -Google Test creates a new test fixture object for each test in order to make +googletest creates a new test fixture object for each test in order to make tests independent and easier to debug. However, sometimes tests use resources that are expensive to set up, making the one-copy-per-test model prohibitively expensive. -If the tests don't change the resource, there's no harm in them sharing a -single resource copy. So, in addition to per-test set-up/tear-down, Google Test +If the tests don't change the resource, there's no harm in their sharing a +single resource copy. So, in addition to per-test set-up/tear-down, googletest also supports per-test-case set-up/tear-down. To use it: - 1. In your test fixture class (say `FooTest` ), define as `static` some member variables to hold the shared resources. - 1. In the same test fixture class, define a `static void SetUpTestCase()` function (remember not to spell it as **`SetupTestCase`** with a small `u`!) to set up the shared resources and a `static void TearDownTestCase()` function to tear them down. +1. In your test fixture class (say `FooTest` ), declare as `static` some member + variables to hold the shared resources. +1. Outside your test fixture class (typically just below it), define those + member variables, optionally giving them initial values. +1. In the same test fixture class, define a `static void SetUpTestCase()` + function (remember not to spell it as **`SetupTestCase`** with a small `u`!) + to set up the shared resources and a `static void TearDownTestCase()` + function to tear them down. -That's it! Google Test automatically calls `SetUpTestCase()` before running the -_first test_ in the `FooTest` test case (i.e. before creating the first -`FooTest` object), and calls `TearDownTestCase()` after running the _last test_ -in it (i.e. after deleting the last `FooTest` object). In between, the tests -can use the shared resources. +That's it! googletest automatically calls `SetUpTestCase()` before running the +*first test* in the `FooTest` test case (i.e. before creating the first +`FooTest` object), and calls `TearDownTestCase()` after running the *last test* +in it (i.e. after deleting the last `FooTest` object). In between, the tests can +use the shared resources. Remember that the test order is undefined, so your code can't depend on a test -preceding or following another. Also, the tests must either not modify the -state of any shared resource, or, if they do modify the state, they must -restore the state to its original value before passing control to the next -test. +preceding or following another. Also, the tests must either not modify the state +of any shared resource, or, if they do modify the state, they must restore the +state to its original value before passing control to the next test. Here's an example of per-test-case set-up and tear-down: -``` + +```c++ class FooTest : public ::testing::Test { protected: // Per-test-case set-up. @@ -1051,8 +1241,10 @@ class FooTest : public ::testing::Test { shared_resource_ = NULL; } - // You can define per-test set-up and tear-down logic as usual. + // You can define per-test set-up logic as usual. virtual void SetUp() { ... } + + // You can define per-test tear-down logic as usual. virtual void TearDown() { ... } // Some expensive resource shared by all tests. @@ -1062,16 +1254,21 @@ class FooTest : public ::testing::Test { T* FooTest::shared_resource_ = NULL; TEST_F(FooTest, Test1) { - ... you can refer to shared_resource here ... + ... you can refer to shared_resource_ here ... } + TEST_F(FooTest, Test2) { - ... you can refer to shared_resource here ... + ... you can refer to shared_resource_ here ... } ``` -_Availability:_ Linux, Windows, Mac. +NOTE: Though the above code declares `SetUpTestCase()` protected, it may +sometimes be necessary to declare it public, such as when using it with +`TEST_P`. -# Global Set-Up and Tear-Down # +**Availability**: Linux, Windows, Mac. + +## Global Set-Up and Tear-Down Just as you can do set-up and tear-down at the test level and the test case level, you can also do it at the test program level. Here's how. @@ -1079,21 +1276,23 @@ level, you can also do it at the test program level. Here's how. First, you subclass the `::testing::Environment` class to define a test environment, which knows how to set-up and tear-down: -``` +```c++ class Environment { public: virtual ~Environment() {} + // Override this to define how to set up the environment. virtual void SetUp() {} + // Override this to define how to tear down the environment. virtual void TearDown() {} }; ``` -Then, you register an instance of your environment class with Google Test by +Then, you register an instance of your environment class with googletest by calling the `::testing::AddGlobalTestEnvironment()` function: -``` +```c++ Environment* AddGlobalTestEnvironment(Environment* env); ``` @@ -1105,79 +1304,58 @@ It's OK to register multiple environment objects. In this case, their `SetUp()` will be called in the order they are registered, and their `TearDown()` will be called in the reverse order. -Note that Google Test takes ownership of the registered environment objects. +Note that googletest takes ownership of the registered environment objects. Therefore **do not delete them** by yourself. -You should call `AddGlobalTestEnvironment()` before `RUN_ALL_TESTS()` is -called, probably in `main()`. If you use `gtest_main`, you need to call -this before `main()` starts for it to take effect. One way to do this is to -define a global variable like this: +You should call `AddGlobalTestEnvironment()` before `RUN_ALL_TESTS()` is called, +probably in `main()`. If you use `gtest_main`, you need to call this before +`main()` starts for it to take effect. One way to do this is to define a global +variable like this: -``` -::testing::Environment* const foo_env = ::testing::AddGlobalTestEnvironment(new FooEnvironment); +```c++ +::testing::Environment* const foo_env = + ::testing::AddGlobalTestEnvironment(new FooEnvironment); ``` However, we strongly recommend you to write your own `main()` and call `AddGlobalTestEnvironment()` there, as relying on initialization of global -variables makes the code harder to read and may cause problems when you -register multiple environments from different translation units and the -environments have dependencies among them (remember that the compiler doesn't -guarantee the order in which global variables from different translation units -are initialized). +variables makes the code harder to read and may cause problems when you register +multiple environments from different translation units and the environments have +dependencies among them (remember that the compiler doesn't guarantee the order +in which global variables from different translation units are initialized). -_Availability:_ Linux, Windows, Mac. +## Value-Parameterized Tests +*Value-parameterized tests* allow you to test your code with different +parameters without writing multiple copies of the same test. This is useful in a +number of situations, for example: -# Value Parameterized Tests # +* You have a piece of code whose behavior is affected by one or more + command-line flags. You want to make sure your code performs correctly for + various values of those flags. +* You want to test different implementations of an OO interface. +* You want to test your code over various inputs (a.k.a. data-driven testing). + This feature is easy to abuse, so please exercise your good sense when doing + it! -_Value-parameterized tests_ allow you to test your code with different -parameters without writing multiple copies of the same test. +### How to Write Value-Parameterized Tests -Suppose you write a test for your code and then realize that your code is affected by a presence of a Boolean command line flag. +To write value-parameterized tests, first you should define a fixture class. It +must be derived from both `::testing::Test` and +`::testing::WithParamInterface` (the latter is a pure interface), where `T` +is the type of your parameter values. For convenience, you can just derive the +fixture class from `::testing::TestWithParam`, which itself is derived from +both `::testing::Test` and `::testing::WithParamInterface`. `T` can be any +copyable type. If it's a raw pointer, you are responsible for managing the +lifespan of the pointed values. -``` -TEST(MyCodeTest, TestFoo) { - // A code to test foo(). -} -``` +NOTE: If your test fixture defines `SetUpTestCase()` or `TearDownTestCase()` +they must be declared **public** rather than **protected** in order to use +`TEST_P`. -Usually people factor their test code into a function with a Boolean parameter in such situations. The function sets the flag, then executes the testing code. - -``` -void TestFooHelper(bool flag_value) { - flag = flag_value; - // A code to test foo(). -} - -TEST(MyCodeTest, TestFoo) { - TestFooHelper(false); - TestFooHelper(true); -} -``` - -But this setup has serious drawbacks. First, when a test assertion fails in your tests, it becomes unclear what value of the parameter caused it to fail. You can stream a clarifying message into your `EXPECT`/`ASSERT` statements, but it you'll have to do it with all of them. Second, you have to add one such helper function per test. What if you have ten tests? Twenty? A hundred? - -Value-parameterized tests will let you write your test only once and then easily instantiate and run it with an arbitrary number of parameter values. - -Here are some other situations when value-parameterized tests come handy: - - * You want to test different implementations of an OO interface. - * You want to test your code over various inputs (a.k.a. data-driven testing). This feature is easy to abuse, so please exercise your good sense when doing it! - -## How to Write Value-Parameterized Tests ## - -To write value-parameterized tests, first you should define a fixture -class. It must be derived from both `::testing::Test` and -`::testing::WithParamInterface` (the latter is a pure interface), -where `T` is the type of your parameter values. For convenience, you -can just derive the fixture class from `::testing::TestWithParam`, -which itself is derived from both `::testing::Test` and -`::testing::WithParamInterface`. `T` can be any copyable type. If -it's a raw pointer, you are responsible for managing the lifespan of -the pointed values. - -``` -class FooTest : public ::testing::TestWithParam { +```c++ +class FooTest : + public ::testing::TestWithParam { // You can implement all the usual fixture class members here. // To access the test parameter, call GetParam() from class // TestWithParam. @@ -1193,11 +1371,11 @@ class BarTest : public BaseTest, }; ``` -Then, use the `TEST_P` macro to define as many test patterns using -this fixture as you want. The `_P` suffix is for "parameterized" or -"pattern", whichever you prefer to think. +Then, use the `TEST_P` macro to define as many test patterns using this fixture +as you want. The `_P` suffix is for "parameterized" or "pattern", whichever you +prefer to think. -``` +```c++ TEST_P(FooTest, DoesBlah) { // Inside a test, access the test parameter with the GetParam() method // of the TestWithParam class: @@ -1210,50 +1388,62 @@ TEST_P(FooTest, HasBlahBlah) { } ``` -Finally, you can use `INSTANTIATE_TEST_CASE_P` to instantiate the test -case with any set of parameters you want. Google Test defines a number of -functions for generating test parameters. They return what we call -(surprise!) _parameter generators_. Here is a summary of them, -which are all in the `testing` namespace: +Finally, you can use `INSTANTIATE_TEST_CASE_P` to instantiate the test case with +any set of parameters you want. googletest defines a number of functions for +generating test parameters. They return what we call (surprise!) *parameter +generators*. Here is a summary of them, which are all in the `testing` +namespace: -| `Range(begin, end[, step])` | Yields values `{begin, begin+step, begin+step+step, ...}`. The values do not include `end`. `step` defaults to 1. | -|:----------------------------|:------------------------------------------------------------------------------------------------------------------| -| `Values(v1, v2, ..., vN)` | Yields values `{v1, v2, ..., vN}`. | -| `ValuesIn(container)` and `ValuesIn(begin, end)` | Yields values from a C-style array, an STL-style container, or an iterator range `[begin, end)`. `container`, `begin`, and `end` can be expressions whose values are determined at run time. | -| `Bool()` | Yields sequence `{false, true}`. | -| `Combine(g1, g2, ..., gN)` | Yields all combinations (the Cartesian product for the math savvy) of the values generated by the `N` generators. This is only available if your system provides the `` header. If you are sure your system does, and Google Test disagrees, you can override it by defining `GTEST_HAS_TR1_TUPLE=1`. See comments in [include/gtest/internal/gtest-port.h](../include/gtest/internal/gtest-port.h) for more information. | +| Parameter Generator | Behavior | +| ---------------------------- | ------------------------------------------- | +| `Range(begin, end [, step])` | Yields values `{begin, begin+step, | +: : begin+step+step, ...}`. The values do not : +: : include `end`. `step` defaults to 1. : +| `Values(v1, v2, ..., vN)` | Yields values `{v1, v2, ..., vN}`. | +| `ValuesIn(container)` and | Yields values from a C-style array, an | +: `ValuesIn(begin,end)` : STL-style container, or an iterator range : +: : `[begin, end)`. : +| `Bool()` | Yields sequence `{false, true}`. | +| `Combine(g1, g2, ..., gN)` | Yields all combinations (Cartesian product) | +: : as std\:\:tuples of the values generated by : +: : the `N` generators. : -For more details, see the comments at the definitions of these functions in the [source code](../include/gtest/gtest-param-test.h). +For more details, see the comments at the definitions of these functions. -The following statement will instantiate tests from the `FooTest` test case -each with parameter values `"meeny"`, `"miny"`, and `"moe"`. +The following statement will instantiate tests from the `FooTest` test case each +with parameter values `"meeny"`, `"miny"`, and `"moe"`. -``` +```c++ INSTANTIATE_TEST_CASE_P(InstantiationName, FooTest, ::testing::Values("meeny", "miny", "moe")); ``` -To distinguish different instances of the pattern (yes, you can -instantiate it more than once), the first argument to -`INSTANTIATE_TEST_CASE_P` is a prefix that will be added to the actual -test case name. Remember to pick unique prefixes for different -instantiations. The tests from the instantiation above will have these -names: +NOTE: The code above must be placed at global or namespace scope, not at +function scope. - * `InstantiationName/FooTest.DoesBlah/0` for `"meeny"` - * `InstantiationName/FooTest.DoesBlah/1` for `"miny"` - * `InstantiationName/FooTest.DoesBlah/2` for `"moe"` - * `InstantiationName/FooTest.HasBlahBlah/0` for `"meeny"` - * `InstantiationName/FooTest.HasBlahBlah/1` for `"miny"` - * `InstantiationName/FooTest.HasBlahBlah/2` for `"moe"` +NOTE: Don't forget this step! If you do your test will silently pass, but none +of its cases will ever run! -You can use these names in [--gtest\_filter](#running-a-subset-of-the-tests). +To distinguish different instances of the pattern (yes, you can instantiate it +more than once), the first argument to `INSTANTIATE_TEST_CASE_P` is a prefix +that will be added to the actual test case name. Remember to pick unique +prefixes for different instantiations. The tests from the instantiation above +will have these names: -This statement will instantiate all tests from `FooTest` again, each -with parameter values `"cat"` and `"dog"`: +* `InstantiationName/FooTest.DoesBlah/0` for `"meeny"` +* `InstantiationName/FooTest.DoesBlah/1` for `"miny"` +* `InstantiationName/FooTest.DoesBlah/2` for `"moe"` +* `InstantiationName/FooTest.HasBlahBlah/0` for `"meeny"` +* `InstantiationName/FooTest.HasBlahBlah/1` for `"miny"` +* `InstantiationName/FooTest.HasBlahBlah/2` for `"moe"` -``` +You can use these names in [`--gtest_filter`](#TestFilter). + +This statement will instantiate all tests from `FooTest` again, each with +parameter values `"cat"` and `"dog"`: + +```c++ const char* pets[] = {"cat", "dog"}; INSTANTIATE_TEST_CASE_P(AnotherInstantiationName, FooTest, ::testing::ValuesIn(pets)); @@ -1261,65 +1451,91 @@ INSTANTIATE_TEST_CASE_P(AnotherInstantiationName, FooTest, The tests from the instantiation above will have these names: - * `AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"` - * `AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"` - * `AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"` - * `AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"` +* `AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"` +* `AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"` +* `AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"` +* `AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"` -Please note that `INSTANTIATE_TEST_CASE_P` will instantiate _all_ -tests in the given test case, whether their definitions come before or -_after_ the `INSTANTIATE_TEST_CASE_P` statement. +Please note that `INSTANTIATE_TEST_CASE_P` will instantiate *all* tests in the +given test case, whether their definitions come before or *after* the +`INSTANTIATE_TEST_CASE_P` statement. -You can see -[these](../samples/sample7_unittest.cc) -[files](../samples/sample8_unittest.cc) for more examples. +You can see sample7_unittest.cc and sample8_unittest.cc for more examples. -_Availability_: Linux, Windows (requires MSVC 8.0 or above), Mac; since version 1.2.0. +**Availability**: Linux, Windows (requires MSVC 8.0 or above), Mac -## Creating Value-Parameterized Abstract Tests ## +### Creating Value-Parameterized Abstract Tests -In the above, we define and instantiate `FooTest` in the same source -file. Sometimes you may want to define value-parameterized tests in a -library and let other people instantiate them later. This pattern is -known as abstract tests. As an example of its application, when you -are designing an interface you can write a standard suite of abstract -tests (perhaps using a factory function as the test parameter) that -all implementations of the interface are expected to pass. When -someone implements the interface, they can instantiate your suite to get -all the interface-conformance tests for free. +In the above, we define and instantiate `FooTest` in the *same* source file. +Sometimes you may want to define value-parameterized tests in a library and let +other people instantiate them later. This pattern is known as *abstract tests*. +As an example of its application, when you are designing an interface you can +write a standard suite of abstract tests (perhaps using a factory function as +the test parameter) that all implementations of the interface are expected to +pass. When someone implements the interface, they can instantiate your suite to +get all the interface-conformance tests for free. To define abstract tests, you should organize your code like this: - 1. Put the definition of the parameterized test fixture class (e.g. `FooTest`) in a header file, say `foo_param_test.h`. Think of this as _declaring_ your abstract tests. - 1. Put the `TEST_P` definitions in `foo_param_test.cc`, which includes `foo_param_test.h`. Think of this as _implementing_ your abstract tests. +1. Put the definition of the parameterized test fixture class (e.g. `FooTest`) + in a header file, say `foo_param_test.h`. Think of this as *declaring* your + abstract tests. +1. Put the `TEST_P` definitions in `foo_param_test.cc`, which includes + `foo_param_test.h`. Think of this as *implementing* your abstract tests. -Once they are defined, you can instantiate them by including -`foo_param_test.h`, invoking `INSTANTIATE_TEST_CASE_P()`, and linking -with `foo_param_test.cc`. You can instantiate the same abstract test -case multiple times, possibly in different source files. +Once they are defined, you can instantiate them by including `foo_param_test.h`, +invoking `INSTANTIATE_TEST_CASE_P()`, and depending on the library target that +contains `foo_param_test.cc`. You can instantiate the same abstract test case +multiple times, possibly in different source files. -# Typed Tests # +### Specifying Names for Value-Parameterized Test Parameters -Suppose you have multiple implementations of the same interface and -want to make sure that all of them satisfy some common requirements. -Or, you may have defined several types that are supposed to conform to -the same "concept" and you want to verify it. In both cases, you want -the same test logic repeated for different types. +The optional last argument to `INSTANTIATE_TEST_CASE_P()` allows the user to +specify a function or functor that generates custom test name suffixes based on +the test parameters. The function should accept one argument of type +`testing::TestParamInfo`, and return `std::string`. -While you can write one `TEST` or `TEST_F` for each type you want to -test (and you may even factor the test logic into a function template -that you invoke from the `TEST`), it's tedious and doesn't scale: -if you want _m_ tests over _n_ types, you'll end up writing _m\*n_ -`TEST`s. +`testing::PrintToStringParamName` is a builtin test suffix generator that +returns the value of `testing::PrintToString(GetParam())`. It does not work for +`std::string` or C strings. -_Typed tests_ allow you to repeat the same test logic over a list of -types. You only need to write the test logic once, although you must -know the type list when writing typed tests. Here's how you do it: +NOTE: test names must be non-empty, unique, and may only contain ASCII +alphanumeric characters. In particular, they [should not contain +underscores](https://g3doc.corp.google.com/third_party/googletest/googletest/g3doc/faq.md#no-underscores). -First, define a fixture class template. It should be parameterized -by a type. Remember to derive it from `::testing::Test`: +```c++ +class MyTestCase : public testing::TestWithParam {}; +TEST_P(MyTestCase, MyTest) +{ + std::cout << "Example Test Param: " << GetParam() << std::endl; +} + +INSTANTIATE_TEST_CASE_P(MyGroup, MyTestCase, testing::Range(0, 10), + testing::PrintToStringParamName()); ``` + +## Typed Tests + +Suppose you have multiple implementations of the same interface and want to make +sure that all of them satisfy some common requirements. Or, you may have defined +several types that are supposed to conform to the same "concept" and you want to +verify it. In both cases, you want the same test logic repeated for different +types. + +While you can write one `TEST` or `TEST_F` for each type you want to test (and +you may even factor the test logic into a function template that you invoke from +the `TEST`), it's tedious and doesn't scale: if you want `m` tests over `n` +types, you'll end up writing `m*n` `TEST`s. + +*Typed tests* allow you to repeat the same test logic over a list of types. You +only need to write the test logic once, although you must know the type list +when writing typed tests. Here's how you do it: + +First, define a fixture class template. It should be parameterized by a type. +Remember to derive it from `::testing::Test`: + +```c++ template class FooTest : public ::testing::Test { public: @@ -1330,22 +1546,22 @@ class FooTest : public ::testing::Test { }; ``` -Next, associate a list of types with the test case, which will be -repeated for each type in the list: +Next, associate a list of types with the test case, which will be repeated for +each type in the list: -``` -typedef ::testing::Types MyTypes; +```c++ +using MyTypes = ::testing::Types; TYPED_TEST_CASE(FooTest, MyTypes); ``` -The `typedef` is necessary for the `TYPED_TEST_CASE` macro to parse -correctly. Otherwise the compiler will think that each comma in the -type list introduces a new macro argument. +The type alias (`using` or `typedef`) is necessary for the `TYPED_TEST_CASE` +macro to parse correctly. Otherwise the compiler will think that each comma in +the type list introduces a new macro argument. -Then, use `TYPED_TEST()` instead of `TEST_F()` to define a typed test -for this test case. You can repeat this as many times as you want: +Then, use `TYPED_TEST()` instead of `TEST_F()` to define a typed test for this +test case. You can repeat this as many times as you want: -``` +```c++ TYPED_TEST(FooTest, DoesBlah) { // Inside a test, refer to the special name TypeParam to get the type // parameter. Since we are inside a derived class template, C++ requires @@ -1359,6 +1575,7 @@ TYPED_TEST(FooTest, DoesBlah) { // To refer to typedefs in the fixture, add the 'typename TestFixture::' // prefix. The 'typename' is required to satisfy the compiler. typename TestFixture::List values; + values.push_back(n); ... } @@ -1366,29 +1583,27 @@ TYPED_TEST(FooTest, DoesBlah) { TYPED_TEST(FooTest, HasPropertyA) { ... } ``` -You can see [`samples/sample6_unittest.cc`](../samples/sample6_unittest.cc) for a complete example. +You can see sample6_unittest.cc -_Availability:_ Linux, Windows (requires MSVC 8.0 or above), Mac; -since version 1.1.0. +**Availability**: Linux, Windows (requires MSVC 8.0 or above), Mac -# Type-Parameterized Tests # +## Type-Parameterized Tests -_Type-parameterized tests_ are like typed tests, except that they -don't require you to know the list of types ahead of time. Instead, -you can define the test logic first and instantiate it with different -type lists later. You can even instantiate it more than once in the -same program. +*Type-parameterized tests* are like typed tests, except that they don't require +you to know the list of types ahead of time. Instead, you can define the test +logic first and instantiate it with different type lists later. You can even +instantiate it more than once in the same program. -If you are designing an interface or concept, you can define a suite -of type-parameterized tests to verify properties that any valid -implementation of the interface/concept should have. Then, the author -of each implementation can just instantiate the test suite with his -type to verify that it conforms to the requirements, without having to -write similar tests repeatedly. Here's an example: +If you are designing an interface or concept, you can define a suite of +type-parameterized tests to verify properties that any valid implementation of +the interface/concept should have. Then, the author of each implementation can +just instantiate the test suite with their type to verify that it conforms to +the requirements, without having to write similar tests repeatedly. Here's an +example: First, define a fixture class template, as we did with typed tests: -``` +```c++ template class FooTest : public ::testing::Test { ... @@ -1397,17 +1612,14 @@ class FooTest : public ::testing::Test { Next, declare that you will define a type-parameterized test case: -``` +```c++ TYPED_TEST_CASE_P(FooTest); ``` -The `_P` suffix is for "parameterized" or "pattern", whichever you -prefer to think. +Then, use `TYPED_TEST_P()` to define a type-parameterized test. You can repeat +this as many times as you want: -Then, use `TYPED_TEST_P()` to define a type-parameterized test. You -can repeat this as many times as you want: - -``` +```c++ TYPED_TEST_P(FooTest, DoesBlah) { // Inside a test, refer to TypeParam to get the type parameter. TypeParam n = 0; @@ -1418,204 +1630,212 @@ TYPED_TEST_P(FooTest, HasPropertyA) { ... } ``` Now the tricky part: you need to register all test patterns using the -`REGISTER_TYPED_TEST_CASE_P` macro before you can instantiate them. -The first argument of the macro is the test case name; the rest are -the names of the tests in this test case: +`REGISTER_TYPED_TEST_CASE_P` macro before you can instantiate them. The first +argument of the macro is the test case name; the rest are the names of the tests +in this test case: -``` +```c++ REGISTER_TYPED_TEST_CASE_P(FooTest, DoesBlah, HasPropertyA); ``` -Finally, you are free to instantiate the pattern with the types you -want. If you put the above code in a header file, you can `#include` -it in multiple C++ source files and instantiate it multiple times. +Finally, you are free to instantiate the pattern with the types you want. If you +put the above code in a header file, you can `#include` it in multiple C++ +source files and instantiate it multiple times. -``` +```c++ typedef ::testing::Types MyTypes; INSTANTIATE_TYPED_TEST_CASE_P(My, FooTest, MyTypes); ``` -To distinguish different instances of the pattern, the first argument -to the `INSTANTIATE_TYPED_TEST_CASE_P` macro is a prefix that will be -added to the actual test case name. Remember to pick unique prefixes -for different instances. +To distinguish different instances of the pattern, the first argument to the +`INSTANTIATE_TYPED_TEST_CASE_P` macro is a prefix that will be added to the +actual test case name. Remember to pick unique prefixes for different instances. -In the special case where the type list contains only one type, you -can write that type directly without `::testing::Types<...>`, like this: +In the special case where the type list contains only one type, you can write +that type directly without `::testing::Types<...>`, like this: -``` +```c++ INSTANTIATE_TYPED_TEST_CASE_P(My, FooTest, int); ``` -You can see `samples/sample6_unittest.cc` for a complete example. +You can see `sample6_unittest.cc` for a complete example. -_Availability:_ Linux, Windows (requires MSVC 8.0 or above), Mac; -since version 1.1.0. +**Availability**: Linux, Windows (requires MSVC 8.0 or above), Mac -# Testing Private Code # +## Testing Private Code If you change your software's internal implementation, your tests should not -break as long as the change is not observable by users. Therefore, per the -_black-box testing principle_, most of the time you should test your code -through its public interfaces. +break as long as the change is not observable by users. Therefore, **per the +black-box testing principle, most of the time you should test your code through +its public interfaces.** -If you still find yourself needing to test internal implementation code, -consider if there's a better design that wouldn't require you to do so. If you -absolutely have to test non-public interface code though, you can. There are -two cases to consider: +**If you still find yourself needing to test internal implementation code, +consider if there's a better design.** The desire to test internal +implementation is often a sign that the class is doing too much. Consider +extracting an implementation class, and testing it. Then use that implementation +class in the original class. - * Static functions (_not_ the same as static member functions!) or unnamed namespaces, and - * Private or protected class members. +If you absolutely have to test non-public interface code though, you can. There +are two cases to consider: -## Static Functions ## +* Static functions ( *not* the same as static member functions!) or unnamed + namespaces, and +* Private or protected class members -Both static functions and definitions/declarations in an unnamed namespace are -only visible within the same translation unit. To test them, you can `#include` -the entire `.cc` file being tested in your `*_test.cc` file. (`#include`ing `.cc` -files is not a good way to reuse code - you should not do this in production -code!) +To test them, we use the following special techniques: -However, a better approach is to move the private code into the -`foo::internal` namespace, where `foo` is the namespace your project normally -uses, and put the private declarations in a `*-internal.h` file. Your -production `.cc` files and your tests are allowed to include this internal -header, but your clients are not. This way, you can fully test your internal -implementation without leaking it to your clients. +* Both static functions and definitions/declarations in an unnamed namespace + are only visible within the same translation unit. To test them, you can + `#include` the entire `.cc` file being tested in your `*_test.cc` file. + (#including `.cc` files is not a good way to reuse code - you should not do + this in production code!) -## Private Class Members ## + However, a better approach is to move the private code into the + `foo::internal` namespace, where `foo` is the namespace your project + normally uses, and put the private declarations in a `*-internal.h` file. + Your production `.cc` files and your tests are allowed to include this + internal header, but your clients are not. This way, you can fully test your + internal implementation without leaking it to your clients. -Private class members are only accessible from within the class or by friends. -To access a class' private members, you can declare your test fixture as a -friend to the class and define accessors in your fixture. Tests using the -fixture can then access the private members of your production class via the -accessors in the fixture. Note that even though your fixture is a friend to -your production class, your tests are not automatically friends to it, as they -are technically defined in sub-classes of the fixture. +* Private class members are only accessible from within the class or by + friends. To access a class' private members, you can declare your test + fixture as a friend to the class and define accessors in your fixture. Tests + using the fixture can then access the private members of your production + class via the accessors in the fixture. Note that even though your fixture + is a friend to your production class, your tests are not automatically + friends to it, as they are technically defined in sub-classes of the + fixture. -Another way to test private members is to refactor them into an implementation -class, which is then declared in a `*-internal.h` file. Your clients aren't -allowed to include this header but your tests can. Such is called the Pimpl -(Private Implementation) idiom. + Another way to test private members is to refactor them into an + implementation class, which is then declared in a `*-internal.h` file. Your + clients aren't allowed to include this header but your tests can. Such is + called the + [Pimpl](https://www.gamedev.net/articles/programming/general-and-gameplay-programming/the-c-pimpl-r1794/) + (Private Implementation) idiom. -Or, you can declare an individual test as a friend of your class by adding this -line in the class body: + Or, you can declare an individual test as a friend of your class by adding + this line in the class body: -``` -FRIEND_TEST(TestCaseName, TestName); -``` + ```c++ + FRIEND_TEST(TestCaseName, TestName); + ``` + + For example, + + ```c++ + // foo.h -For example, -``` -// foo.h #include "gtest/gtest_prod.h" -// Defines FRIEND_TEST. -class Foo { - ... - private: - FRIEND_TEST(FooTest, BarReturnsZeroOnNull); - int Bar(void* x); -}; + class Foo { + ... + private: + FRIEND_TEST(FooTest, BarReturnsZeroOnNull); -// foo_test.cc -... -TEST(FooTest, BarReturnsZeroOnNull) { - Foo foo; - EXPECT_EQ(0, foo.Bar(NULL)); - // Uses Foo's private member Bar(). -} + int Bar(void* x); + }; + + // foo_test.cc + ... + TEST(FooTest, BarReturnsZeroOnNull) { + Foo foo; + EXPECT_EQ(0, foo.Bar(NULL)); // Uses Foo's private member Bar(). + } + ``` + + Pay special attention when your class is defined in a namespace, as you + should define your test fixtures and tests in the same namespace if you want + them to be friends of your class. For example, if the code to be tested + looks like: + + ```c++ + namespace my_namespace { + + class Foo { + friend class FooTest; + FRIEND_TEST(FooTest, Bar); + FRIEND_TEST(FooTest, Baz); + ... definition of the class Foo ... + }; + + } // namespace my_namespace + ``` + + Your test code should be something like: + + ```c++ + namespace my_namespace { + + class FooTest : public ::testing::Test { + protected: + ... + }; + + TEST_F(FooTest, Bar) { ... } + TEST_F(FooTest, Baz) { ... } + + } // namespace my_namespace + ``` + + + ## "Catching" Failures + +If you are building a testing utility on top of googletest, you'll want to test +your utility. What framework would you use to test it? googletest, of course. + +The challenge is to verify that your testing utility reports failures correctly. +In frameworks that report a failure by throwing an exception, you could catch +the exception and assert on it. But googletest doesn't use exceptions, so how do +we test that a piece of code generates an expected failure? + +gunit-spi.h contains some constructs to do this. After #including this header, +you can use + +```c++ + EXPECT_FATAL_FAILURE(statement, substring); ``` -Pay special attention when your class is defined in a namespace, as you should -define your test fixtures and tests in the same namespace if you want them to -be friends of your class. For example, if the code to be tested looks like: +to assert that `statement` generates a fatal (e.g. `ASSERT_*`) failure in the +current thread whose message contains the given `substring`, or use +```c++ + EXPECT_NONFATAL_FAILURE(statement, substring); ``` -namespace my_namespace { - -class Foo { - friend class FooTest; - FRIEND_TEST(FooTest, Bar); - FRIEND_TEST(FooTest, Baz); - ... - definition of the class Foo - ... -}; - -} // namespace my_namespace -``` - -Your test code should be something like: - -``` -namespace my_namespace { -class FooTest : public ::testing::Test { - protected: - ... -}; - -TEST_F(FooTest, Bar) { ... } -TEST_F(FooTest, Baz) { ... } - -} // namespace my_namespace -``` - -# Catching Failures # - -If you are building a testing utility on top of Google Test, you'll -want to test your utility. What framework would you use to test it? -Google Test, of course. - -The challenge is to verify that your testing utility reports failures -correctly. In frameworks that report a failure by throwing an -exception, you could catch the exception and assert on it. But Google -Test doesn't use exceptions, so how do we test that a piece of code -generates an expected failure? - -`"gtest/gtest-spi.h"` contains some constructs to do this. After -`#include`ing this header, you can use - -| `EXPECT_FATAL_FAILURE(`_statement, substring_`);` | -|:--------------------------------------------------| - -to assert that _statement_ generates a fatal (e.g. `ASSERT_*`) failure -whose message contains the given _substring_, or use - -| `EXPECT_NONFATAL_FAILURE(`_statement, substring_`);` | -|:-----------------------------------------------------| if you are expecting a non-fatal (e.g. `EXPECT_*`) failure. +Only failures in the current thread are checked to determine the result of this +type of expectations. If `statement` creates new threads, failures in these +threads are also ignored. If you want to catch failures in other threads as +well, use one of the following macros instead: + +```c++ + EXPECT_FATAL_FAILURE_ON_ALL_THREADS(statement, substring); + EXPECT_NONFATAL_FAILURE_ON_ALL_THREADS(statement, substring); +``` + +NOTE: Assertions from multiple threads are currently not supported on Windows. + For technical reasons, there are some caveats: - 1. You cannot stream a failure message to either macro. - 1. _statement_ in `EXPECT_FATAL_FAILURE()` cannot reference local non-static variables or non-static members of `this` object. - 1. _statement_ in `EXPECT_FATAL_FAILURE()` cannot return a value. +1. You cannot stream a failure message to either macro. -_Note:_ Google Test is designed with threads in mind. Once the -synchronization primitives in `"gtest/internal/gtest-port.h"` have -been implemented, Google Test will become thread-safe, meaning that -you can then use assertions in multiple threads concurrently. Before -that, however, Google Test only supports single-threaded usage. Once -thread-safe, `EXPECT_FATAL_FAILURE()` and `EXPECT_NONFATAL_FAILURE()` -will capture failures in the current thread only. If _statement_ -creates new threads, failures in these threads will be ignored. If -you want to capture failures from all threads instead, you should use -the following macros: +1. `statement` in `EXPECT_FATAL_FAILURE{_ON_ALL_THREADS}()` cannot reference + local non-static variables or non-static members of `this` object. -| `EXPECT_FATAL_FAILURE_ON_ALL_THREADS(`_statement, substring_`);` | -|:-----------------------------------------------------------------| -| `EXPECT_NONFATAL_FAILURE_ON_ALL_THREADS(`_statement, substring_`);` | +1. `statement` in `EXPECT_FATAL_FAILURE{_ON_ALL_THREADS}()()` cannot return a + value. -# Getting the Current Test's Name # + +## Getting the Current Test's Name Sometimes a function may need to know the name of the currently running test. For example, you may be using the `SetUp()` method of your test fixture to set the golden file name based on which test is running. The `::testing::TestInfo` class has this information: -``` +```c++ namespace testing { class TestInfo { @@ -1628,65 +1848,68 @@ class TestInfo { const char* name() const; }; -} // namespace testing +} ``` - -> To obtain a `TestInfo` object for the currently running test, call +To obtain a `TestInfo` object for the currently running test, call `current_test_info()` on the `UnitTest` singleton object: -``` -// Gets information about the currently running test. -// Do NOT delete the returned object - it's managed by the UnitTest class. -const ::testing::TestInfo* const test_info = - ::testing::UnitTest::GetInstance()->current_test_info(); -printf("We are in test %s of test case %s.\n", - test_info->name(), test_info->test_case_name()); +```c++ + // Gets information about the currently running test. + // Do NOT delete the returned object - it's managed by the UnitTest class. + const ::testing::TestInfo* const test_info = + ::testing::UnitTest::GetInstance()->current_test_info(); + + + + printf("We are in test %s of test case %s.\n", + test_info->name(), + test_info->test_case_name()); ``` `current_test_info()` returns a null pointer if no test is running. In -particular, you cannot find the test case name in `SetUpTestCase()`, -`TearDownTestCase()` (where you know the test case name implicitly), or +particular, you cannot find the test case name in `TestCaseSetUp()`, +`TestCaseTearDown()` (where you know the test case name implicitly), or functions called from them. -_Availability:_ Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -# Extending Google Test by Handling Test Events # +## Extending googletest by Handling Test Events -Google Test provides an event listener API to let you receive -notifications about the progress of a test program and test -failures. The events you can listen to include the start and end of -the test program, a test case, or a test method, among others. You may -use this API to augment or replace the standard console output, -replace the XML output, or provide a completely different form of -output, such as a GUI or a database. You can also use test events as +googletest provides an **event listener API** to let you receive notifications +about the progress of a test program and test failures. The events you can +listen to include the start and end of the test program, a test case, or a test +method, among others. You may use this API to augment or replace the standard +console output, replace the XML output, or provide a completely different form +of output, such as a GUI or a database. You can also use test events as checkpoints to implement a resource leak checker, for example. -_Availability:_ Linux, Windows, Mac; since v1.4.0. +**Availability**: Linux, Windows, Mac. -## Defining Event Listeners ## +### Defining Event Listeners -To define a event listener, you subclass either -[testing::TestEventListener](../include/gtest/gtest.h#L991) -or [testing::EmptyTestEventListener](../include/gtest/gtest.h#L1044). -The former is an (abstract) interface, where each pure virtual method
-can be overridden to handle a test event (For example, when a test -starts, the `OnTestStart()` method will be called.). The latter provides -an empty implementation of all methods in the interface, such that a -subclass only needs to override the methods it cares about. +To define a event listener, you subclass either testing::TestEventListener or +testing::EmptyTestEventListener The former is an (abstract) interface, where +*each pure virtual method can be overridden to handle a test event* (For +example, when a test starts, the `OnTestStart()` method will be called.). The +latter provides an empty implementation of all methods in the interface, such +that a subclass only needs to override the methods it cares about. -When an event is fired, its context is passed to the handler function -as an argument. The following argument types are used: - * [UnitTest](../include/gtest/gtest.h#L1151) reflects the state of the entire test program, - * [TestCase](../include/gtest/gtest.h#L778) has information about a test case, which can contain one or more tests, - * [TestInfo](../include/gtest/gtest.h#L644) contains the state of a test, and - * [TestPartResult](../include/gtest/gtest-test-part.h#L47) represents the result of a test assertion. +When an event is fired, its context is passed to the handler function as an +argument. The following argument types are used: -An event handler function can examine the argument it receives to find -out interesting information about the event and the test program's -state. Here's an example: +* UnitTest reflects the state of the entire test program, +* TestCase has information about a test case, which can contain one or more + tests, +* TestInfo contains the state of a test, and +* TestPartResult represents the result of a test assertion. -``` +An event handler function can examine the argument it receives to find out +interesting information about the event and the test program's state. + +Here's an example: + +```c++ class MinimalistPrinter : public ::testing::EmptyTestEventListener { // Called before a test starts. virtual void OnTestStart(const ::testing::TestInfo& test_info) { @@ -1694,9 +1917,8 @@ state. Here's an example: test_info.test_case_name(), test_info.name()); } - // Called after a failed assertion or a SUCCEED() invocation. - virtual void OnTestPartResult( - const ::testing::TestPartResult& test_part_result) { + // Called after a failed assertion or a SUCCESS(). + virtual void OnTestPartResult(const ::testing::TestPartResult& test_part_result) { printf("%s in %s:%d\n%s\n", test_part_result.failed() ? "*** Failure" : "Success", test_part_result.file_name(), @@ -1712,105 +1934,88 @@ state. Here's an example: }; ``` -## Using Event Listeners ## +### Using Event Listeners -To use the event listener you have defined, add an instance of it to -the Google Test event listener list (represented by class -[TestEventListeners](../include/gtest/gtest.h#L1064) -- note the "s" at the end of the name) in your -`main()` function, before calling `RUN_ALL_TESTS()`: -``` +To use the event listener you have defined, add an instance of it to the +googletest event listener list (represented by class TestEventListeners - note +the "s" at the end of the name) in your `main()` function, before calling +`RUN_ALL_TESTS()`: + +```c++ int main(int argc, char** argv) { ::testing::InitGoogleTest(&argc, argv); // Gets hold of the event listener list. ::testing::TestEventListeners& listeners = - ::testing::UnitTest::GetInstance()->listeners(); - // Adds a listener to the end. Google Test takes the ownership. + ::testing::UnitTest::GetInstance()->listeners(); + // Adds a listener to the end. googletest takes the ownership. listeners.Append(new MinimalistPrinter); return RUN_ALL_TESTS(); } ``` -There's only one problem: the default test result printer is still in -effect, so its output will mingle with the output from your minimalist -printer. To suppress the default printer, just release it from the -event listener list and delete it. You can do so by adding one line: -``` +There's only one problem: the default test result printer is still in effect, so +its output will mingle with the output from your minimalist printer. To suppress +the default printer, just release it from the event listener list and delete it. +You can do so by adding one line: + +```c++ ... delete listeners.Release(listeners.default_result_printer()); listeners.Append(new MinimalistPrinter); return RUN_ALL_TESTS(); ``` -Now, sit back and enjoy a completely different output from your -tests. For more details, you can read this -[sample](../samples/sample9_unittest.cc). +Now, sit back and enjoy a completely different output from your tests. For more +details, you can read this sample9_unittest.cc -You may append more than one listener to the list. When an `On*Start()` -or `OnTestPartResult()` event is fired, the listeners will receive it in -the order they appear in the list (since new listeners are added to -the end of the list, the default text printer and the default XML -generator will receive the event first). An `On*End()` event will be -received by the listeners in the _reverse_ order. This allows output by -listeners added later to be framed by output from listeners added -earlier. +You may append more than one listener to the list. When an `On*Start()` or +`OnTestPartResult()` event is fired, the listeners will receive it in the order +they appear in the list (since new listeners are added to the end of the list, +the default text printer and the default XML generator will receive the event +first). An `On*End()` event will be received by the listeners in the *reverse* +order. This allows output by listeners added later to be framed by output from +listeners added earlier. -## Generating Failures in Listeners ## +### Generating Failures in Listeners -You may use failure-raising macros (`EXPECT_*()`, `ASSERT_*()`, -`FAIL()`, etc) when processing an event. There are some restrictions: +You may use failure-raising macros (`EXPECT_*()`, `ASSERT_*()`, `FAIL()`, etc) +when processing an event. There are some restrictions: - 1. You cannot generate any failure in `OnTestPartResult()` (otherwise it will cause `OnTestPartResult()` to be called recursively). - 1. A listener that handles `OnTestPartResult()` is not allowed to generate any failure. +1. You cannot generate any failure in `OnTestPartResult()` (otherwise it will + cause `OnTestPartResult()` to be called recursively). +1. A listener that handles `OnTestPartResult()` is not allowed to generate any + failure. -When you add listeners to the listener list, you should put listeners -that handle `OnTestPartResult()` _before_ listeners that can generate -failures. This ensures that failures generated by the latter are -attributed to the right test by the former. +When you add listeners to the listener list, you should put listeners that +handle `OnTestPartResult()` *before* listeners that can generate failures. This +ensures that failures generated by the latter are attributed to the right test +by the former. -We have a sample of failure-raising listener -[here](../samples/sample10_unittest.cc). +We have a sample of failure-raising listener sample10_unittest.cc -# Running Test Programs: Advanced Options # +## Running Test Programs: Advanced Options -Google Test test programs are ordinary executables. Once built, you can run -them directly and affect their behavior via the following environment variables +googletest test programs are ordinary executables. Once built, you can run them +directly and affect their behavior via the following environment variables and/or command line flags. For the flags to work, your programs must call `::testing::InitGoogleTest()` before calling `RUN_ALL_TESTS()`. -To see a list of supported flags and their usage, please run your test -program with the `--help` flag. You can also use `-h`, `-?`, or `/?` -for short. This feature is added in version 1.3.0. +To see a list of supported flags and their usage, please run your test program +with the `--help` flag. You can also use `-h`, `-?`, or `/?` for short. -If an option is specified both by an environment variable and by a -flag, the latter takes precedence. Most of the options can also be -set/read in code: to access the value of command line flag -`--gtest_foo`, write `::testing::GTEST_FLAG(foo)`. A common pattern is -to set the value of a flag before calling `::testing::InitGoogleTest()` -to change the default value of the flag: -``` -int main(int argc, char** argv) { - // Disables elapsed time by default. - ::testing::GTEST_FLAG(print_time) = false; +If an option is specified both by an environment variable and by a flag, the +latter takes precedence. - // This allows the user to override the flag on the command line. - ::testing::InitGoogleTest(&argc, argv); +### Selecting Tests - return RUN_ALL_TESTS(); -} -``` - -## Selecting Tests ## - -This section shows various options for choosing which tests to run. - -### Listing Test Names ### +#### Listing Test Names Sometimes it is necessary to list the available tests in a program before running them so that a filter may be applied if needed. Including the flag `--gtest_list_tests` overrides all other flags and lists tests in the following format: -``` + +```none TestCase1. TestName1 TestName2 @@ -1821,39 +2026,44 @@ TestCase2. None of the tests listed are actually run if the flag is provided. There is no corresponding environment variable for this flag. -_Availability:_ Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -### Running a Subset of the Tests ### +#### Running a Subset of the Tests -By default, a Google Test program runs all tests the user has defined. -Sometimes, you want to run only a subset of the tests (e.g. for debugging or -quickly verifying a change). If you set the `GTEST_FILTER` environment variable -or the `--gtest_filter` flag to a filter string, Google Test will only run the -tests whose full names (in the form of `TestCaseName.TestName`) match the -filter. +By default, a googletest program runs all tests the user has defined. Sometimes, +you want to run only a subset of the tests (e.g. for debugging or quickly +verifying a change). If you set the `GTEST_FILTER` environment variable or the +`--gtest_filter` flag to a filter string, googletest will only run the tests +whose full names (in the form of `TestCaseName.TestName`) match the filter. The format of a filter is a '`:`'-separated list of wildcard patterns (called -the positive patterns) optionally followed by a '`-`' and another -'`:`'-separated pattern list (called the negative patterns). A test matches the -filter if and only if it matches any of the positive patterns but does not +the *positive patterns*) optionally followed by a '`-`' and another +'`:`'-separated pattern list (called the *negative patterns*). A test matches +the filter if and only if it matches any of the positive patterns but does not match any of the negative patterns. A pattern may contain `'*'` (matches any string) or `'?'` (matches any single -character). For convenience, the filter `'*-NegativePatterns'` can be also -written as `'-NegativePatterns'`. +character). For convenience, the filter + +`'*-NegativePatterns'` can be also written as `'-NegativePatterns'`. For example: - * `./foo_test` Has no flag, and thus runs all its tests. - * `./foo_test --gtest_filter=*` Also runs everything, due to the single match-everything `*` value. - * `./foo_test --gtest_filter=FooTest.*` Runs everything in test case `FooTest`. - * `./foo_test --gtest_filter=*Null*:*Constructor*` Runs any test whose full name contains either `"Null"` or `"Constructor"`. - * `./foo_test --gtest_filter=-*DeathTest.*` Runs all non-death tests. - * `./foo_test --gtest_filter=FooTest.*-FooTest.Bar` Runs everything in test case `FooTest` except `FooTest.Bar`. - -_Availability:_ Linux, Windows, Mac. - -### Temporarily Disabling Tests ### +* `./foo_test` Has no flag, and thus runs all its tests. +* `./foo_test --gtest_filter=*` Also runs everything, due to the single + match-everything `*` value. +* `./foo_test --gtest_filter=FooTest.*` Runs everything in test case `FooTest` + . +* `./foo_test --gtest_filter=*Null*:*Constructor*` Runs any test whose full + name contains either `"Null"` or `"Constructor"` . +* `./foo_test --gtest_filter=-*DeathTest.*` Runs all non-death tests. +* `./foo_test --gtest_filter=FooTest.*-FooTest.Bar` Runs everything in test + case `FooTest` except `FooTest.Bar`. +* `./foo_test --gtest_filter=FooTest.*:BarTest.*-FooTest.Bar:BarTest.Foo` Runs + everything in test case `FooTest` except `FooTest.Bar` and everything in + test case `BarTest` except `BarTest.Foo`. + +#### Temporarily Disabling Tests If you have a broken test that you cannot fix right away, you can add the `DISABLED_` prefix to its name. This will exclude it from execution. This is @@ -1864,10 +2074,10 @@ If you need to disable all tests in a test case, you can either add `DISABLED_` to the front of the name of each test, or alternatively add it to the front of the test case name. -For example, the following tests won't be run by Google Test, even though they +For example, the following tests won't be run by googletest, even though they will still be compiled: -``` +```c++ // Tests that Foo does Abc. TEST(FooTest, DISABLED_DoesAbc) { ... } @@ -1877,140 +2087,164 @@ class DISABLED_BarTest : public ::testing::Test { ... }; TEST_F(DISABLED_BarTest, DoesXyz) { ... } ``` -_Note:_ This feature should only be used for temporary pain-relief. You still -have to fix the disabled tests at a later date. As a reminder, Google Test will -print a banner warning you if a test program contains any disabled tests. +NOTE: This feature should only be used for temporary pain-relief. You still have +to fix the disabled tests at a later date. As a reminder, googletest will print +a banner warning you if a test program contains any disabled tests. -_Tip:_ You can easily count the number of disabled tests you have -using `grep`. This number can be used as a metric for improving your -test quality. +TIP: You can easily count the number of disabled tests you have using `gsearch` +and/or `grep`. This number can be used as a metric for improving your test +quality. -_Availability:_ Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -### Temporarily Enabling Disabled Tests ### +#### Temporarily Enabling Disabled Tests -To include [disabled tests](#temporarily-disabling-tests) in test -execution, just invoke the test program with the -`--gtest_also_run_disabled_tests` flag or set the -`GTEST_ALSO_RUN_DISABLED_TESTS` environment variable to a value other -than `0`. You can combine this with the -[--gtest\_filter](#running-a-subset-of-the-tests) flag to further select -which disabled tests to run. +To include disabled tests in test execution, just invoke the test program with +the `--gtest_also_run_disabled_tests` flag or set the +`GTEST_ALSO_RUN_DISABLED_TESTS` environment variable to a value other than `0`. +You can combine this with the `--gtest_filter` flag to further select which +disabled tests to run. -_Availability:_ Linux, Windows, Mac; since version 1.3.0. +**Availability**: Linux, Windows, Mac. -## Repeating the Tests ## +### Repeating the Tests Once in a while you'll run into a test whose result is hit-or-miss. Perhaps it will fail only 1% of the time, making it rather hard to reproduce the bug under a debugger. This can be a major source of frustration. -The `--gtest_repeat` flag allows you to repeat all (or selected) test methods -in a program many times. Hopefully, a flaky test will eventually fail and give -you a chance to debug. Here's how to use it: +The `--gtest_repeat` flag allows you to repeat all (or selected) test methods in +a program many times. Hopefully, a flaky test will eventually fail and give you +a chance to debug. Here's how to use it: -| `$ foo_test --gtest_repeat=1000` | Repeat foo\_test 1000 times and don't stop at failures. | -|:---------------------------------|:--------------------------------------------------------| -| `$ foo_test --gtest_repeat=-1` | A negative count means repeating forever. | -| `$ foo_test --gtest_repeat=1000 --gtest_break_on_failure` | Repeat foo\_test 1000 times, stopping at the first failure. This is especially useful when running under a debugger: when the testfails, it will drop into the debugger and you can then inspect variables and stacks. | -| `$ foo_test --gtest_repeat=1000 --gtest_filter=FooBar` | Repeat the tests whose name matches the filter 1000 times. | +```none +$ foo_test --gtest_repeat=1000 +Repeat foo_test 1000 times and don't stop at failures. -If your test program contains global set-up/tear-down code registered -using `AddGlobalTestEnvironment()`, it will be repeated in each -iteration as well, as the flakiness may be in it. You can also specify -the repeat count by setting the `GTEST_REPEAT` environment variable. +$ foo_test --gtest_repeat=-1 +A negative count means repeating forever. -_Availability:_ Linux, Windows, Mac. +$ foo_test --gtest_repeat=1000 --gtest_break_on_failure +Repeat foo_test 1000 times, stopping at the first failure. This +is especially useful when running under a debugger: when the test +fails, it will drop into the debugger and you can then inspect +variables and stacks. -## Shuffling the Tests ## +$ foo_test --gtest_repeat=1000 --gtest_filter=FooBar.* +Repeat the tests whose name matches the filter 1000 times. +``` + +If your test program contains [global set-up/tear-down](#GlobalSetUp) code, it +will be repeated in each iteration as well, as the flakiness may be in it. You +can also specify the repeat count by setting the `GTEST_REPEAT` environment +variable. + +**Availability**: Linux, Windows, Mac. + +### Shuffling the Tests You can specify the `--gtest_shuffle` flag (or set the `GTEST_SHUFFLE` -environment variable to `1`) to run the tests in a program in a random -order. This helps to reveal bad dependencies between tests. +environment variable to `1`) to run the tests in a program in a random order. +This helps to reveal bad dependencies between tests. -By default, Google Test uses a random seed calculated from the current -time. Therefore you'll get a different order every time. The console -output includes the random seed value, such that you can reproduce an -order-related test failure later. To specify the random seed -explicitly, use the `--gtest_random_seed=SEED` flag (or set the -`GTEST_RANDOM_SEED` environment variable), where `SEED` is an integer -between 0 and 99999. The seed value 0 is special: it tells Google Test -to do the default behavior of calculating the seed from the current +By default, googletest uses a random seed calculated from the current time. +Therefore you'll get a different order every time. The console output includes +the random seed value, such that you can reproduce an order-related test failure +later. To specify the random seed explicitly, use the `--gtest_random_seed=SEED` +flag (or set the `GTEST_RANDOM_SEED` environment variable), where `SEED` is an +integer in the range [0, 99999]. The seed value 0 is special: it tells +googletest to do the default behavior of calculating the seed from the current time. -If you combine this with `--gtest_repeat=N`, Google Test will pick a -different random seed and re-shuffle the tests in each iteration. +If you combine this with `--gtest_repeat=N`, googletest will pick a different +random seed and re-shuffle the tests in each iteration. -_Availability:_ Linux, Windows, Mac; since v1.4.0. +**Availability**: Linux, Windows, Mac. -## Controlling Test Output ## +### Controlling Test Output -This section teaches how to tweak the way test results are reported. +#### Colored Terminal Output -### Colored Terminal Output ### +googletest can use colors in its terminal output to make it easier to spot the +important information: -Google Test can use colors in its terminal output to make it easier to spot -the separation between tests, and whether tests passed. +... +[----------] 1 test from FooTest +[ RUN ] FooTest.DoesAbc +[ OK ] FooTest.DoesAbc +[----------] 2 tests from BarTest +[ RUN ] BarTest.HasXyzProperty +[ OK ] BarTest.HasXyzProperty +[ RUN ] BarTest.ReturnsTrueOnSuccess +... some error messages ... +[ FAILED ] BarTest.ReturnsTrueOnSuccess +... +[==========] 30 tests from 14 test cases ran. +[ PASSED ] 28 tests. +[ FAILED ] 2 tests, listed below: +[ FAILED ] BarTest.ReturnsTrueOnSuccess +[ FAILED ] AnotherTest.DoesXyz -You can set the GTEST\_COLOR environment variable or set the `--gtest_color` + 2 FAILED TESTS + +You can set the `GTEST_COLOR` environment variable or the `--gtest_color` command line flag to `yes`, `no`, or `auto` (the default) to enable colors, -disable colors, or let Google Test decide. When the value is `auto`, Google -Test will use colors if and only if the output goes to a terminal and (on -non-Windows platforms) the `TERM` environment variable is set to `xterm` or -`xterm-color`. +disable colors, or let googletest decide. When the value is `auto`, googletest +will use colors if and only if the output goes to a terminal and (on non-Windows +platforms) the `TERM` environment variable is set to `xterm` or `xterm-color`. -_Availability:_ Linux, Windows, Mac. +> +> **Availability**: Linux, Windows, Mac. -### Suppressing the Elapsed Time ### +#### Suppressing the Elapsed Time -By default, Google Test prints the time it takes to run each test. To -suppress that, run the test program with the `--gtest_print_time=0` -command line flag. Setting the `GTEST_PRINT_TIME` environment -variable to `0` has the same effect. - -_Availability:_ Linux, Windows, Mac. (In Google Test 1.3.0 and lower, -the default behavior is that the elapsed time is **not** printed.) +By default, googletest prints the time it takes to run each test. To disable +that, run the test program with the `--gtest_print_time=0` command line flag, or +set the GTEST_PRINT_TIME environment variable to `0`. **Availability**: Linux, Windows, Mac. #### Suppressing UTF-8 Text Output -In case of assertion failures, gUnit prints expected and actual values of type -`string` both as hex-encoded strings as well as in readable UTF-8 text if they -contain valid non-ASCII UTF-8 characters. If you want to suppress the UTF-8 text -because, for example, you don't have an UTF-8 compatible output medium, run the -test program with `--gunit_print_utf8=0` or set the `GUNIT_PRINT_UTF8` +In case of assertion failures, googletest prints expected and actual values of +type `string` both as hex-encoded strings as well as in readable UTF-8 text if +they contain valid non-ASCII UTF-8 characters. If you want to suppress the UTF-8 +text because, for example, you don't have an UTF-8 compatible output medium, run +the test program with `--gtest_print_utf8=0` or set the `GTEST_PRINT_UTF8` environment variable to `0`. -### Generating an XML Report ### +**Availability**: Linux, Windows, Mac. -Google Test can emit a detailed XML report to a file in addition to its normal -textual output. The report contains the duration of each test, and thus can -help you identify slow tests. + +#### Generating an XML Report + +googletest can emit a detailed XML report to a file in addition to its normal +textual output. The report contains the duration of each test, and thus can help +you identify slow tests. The report is also used by the http://unittest +dashboard to show per-test-method error messages. To generate the XML report, set the `GTEST_OUTPUT` environment variable or the -`--gtest_output` flag to the string `"xml:_path_to_output_file_"`, which will -create the file at the given location. You can also just use the string -`"xml"`, in which case the output can be found in the `test_detail.xml` file in -the current directory. +`--gtest_output` flag to the string `"xml:path_to_output_file"`, which will +create the file at the given location. You can also just use the string `"xml"`, +in which case the output can be found in the `test_detail.xml` file in the +current directory. If you specify a directory (for example, `"xml:output/directory/"` on Linux or -`"xml:output\directory\"` on Windows), Google Test will create the XML file in +`"xml:output\directory\"` on Windows), googletest will create the XML file in that directory, named after the test executable (e.g. `foo_test.xml` for test program `foo_test` or `foo_test.exe`). If the file already exists (perhaps left -over from a previous run), Google Test will pick a different name (e.g. +over from a previous run), googletest will pick a different name (e.g. `foo_test_1.xml`) to avoid overwriting it. -The report uses the format described here. It is based on the -`junitreport` Ant task and can be parsed by popular continuous build -systems like [Hudson](https://hudson.dev.java.net/). Since that format -was originally intended for Java, a little interpretation is required -to make it apply to Google Test tests, as shown here: -``` +The report is based on the `junitreport` Ant task. Since that format was +originally intended for Java, a little interpretation is required to make it +apply to googletest tests, as shown here: + +```xml - + @@ -2019,13 +2253,13 @@ to make it apply to Google Test tests, as shown here: ``` - * The root `` element corresponds to the entire test program. - * `` elements correspond to Google Test test cases. - * `` elements correspond to Google Test test functions. +* The root `` element corresponds to the entire test program. +* `` elements correspond to googletest test cases. +* `` elements correspond to googletest test functions. For instance, the following program -``` +```c++ TEST(MathTest, Addition) { ... } TEST(MathTest, Subtraction) { ... } TEST(LogicTest, NonContradiction) { ... } @@ -2033,19 +2267,19 @@ TEST(LogicTest, NonContradiction) { ... } could generate this report: -``` +```xml - - - - - + + + + ... + ... - + - - + + @@ -2053,18 +2287,26 @@ could generate this report: Things to note: - * The `tests` attribute of a `` or `` element tells how many test functions the Google Test program or test case contains, while the `failures` attribute tells how many of them failed. - * The `time` attribute expresses the duration of the test, test case, or entire test program in milliseconds. - * Each `` element corresponds to a single failed Google Test assertion. - * Some JUnit concepts don't apply to Google Test, yet we have to conform to the DTD. Therefore you'll see some dummy elements and attributes in the report. You can safely ignore these parts. +* The `tests` attribute of a `` or `` element tells how + many test functions the googletest program or test case contains, while the + `failures` attribute tells how many of them failed. -_Availability:_ Linux, Windows, Mac. +* The `time` attribute expresses the duration of the test, test case, or + entire test program in seconds. -#### Generating an JSON Report {#JsonReport} +* The `timestamp` attribute records the local date and time of the test + execution. -gUnit can also emit a JSON report as an alternative format to XML. To generate -the JSON report, set the `GUNIT_OUTPUT` environment variable or the -`--gunit_output` flag to the string `"json:path_to_output_file"`, which will +* Each `` element corresponds to a single failed googletest + assertion. + +**Availability**: Linux, Windows, Mac. + +#### Generating an JSON Report + +googletest can also emit a JSON report as an alternative format to XML. To +generate the JSON report, set the `GTEST_OUTPUT` environment variable or the +`--gtest_output` flag to the string `"json:path_to_output_file"`, which will create the file at the given location. You can also just use the string `"json"`, in which case the output can be found in the `test_detail.json` file in the current directory. @@ -2139,8 +2381,8 @@ The report format conforms to the following JSON Schema: } ``` -The report uses the format that conforms to the following Proto3 using the -[JSON encoding](https://developers.google.com/protocol-buffers/docs/proto3#json): +The report uses the format that conforms to the following Proto3 using the [JSON +encoding](https://developers.google.com/protocol-buffers/docs/proto3#json): ```proto syntax = "proto3"; @@ -2261,156 +2503,34 @@ IMPORTANT: The exact format of the JSON document is subject to change. **Availability**: Linux, Windows, Mac. -## Controlling How Failures Are Reported ## +### Controlling How Failures Are Reported -### Turning Assertion Failures into Break-Points ### +#### Turning Assertion Failures into Break-Points When running test programs under a debugger, it's very convenient if the debugger can catch an assertion failure and automatically drop into interactive -mode. Google Test's _break-on-failure_ mode supports this behavior. +mode. googletest's *break-on-failure* mode supports this behavior. To enable it, set the `GTEST_BREAK_ON_FAILURE` environment variable to a value other than `0` . Alternatively, you can use the `--gtest_break_on_failure` command line flag. -_Availability:_ Linux, Windows, Mac. +**Availability**: Linux, Windows, Mac. -### Disabling Catching Test-Thrown Exceptions ### +#### Disabling Catching Test-Thrown Exceptions -Google Test can be used either with or without exceptions enabled. If -a test throws a C++ exception or (on Windows) a structured exception -(SEH), by default Google Test catches it, reports it as a test -failure, and continues with the next test method. This maximizes the -coverage of a test run. Also, on Windows an uncaught exception will -cause a pop-up window, so catching the exceptions allows you to run -the tests automatically. +googletest can be used either with or without exceptions enabled. If a test +throws a C++ exception or (on Windows) a structured exception (SEH), by default +googletest catches it, reports it as a test failure, and continues with the next +test method. This maximizes the coverage of a test run. Also, on Windows an +uncaught exception will cause a pop-up window, so catching the exceptions allows +you to run the tests automatically. -When debugging the test failures, however, you may instead want the -exceptions to be handled by the debugger, such that you can examine -the call stack when an exception is thrown. To achieve that, set the -`GTEST_CATCH_EXCEPTIONS` environment variable to `0`, or use the -`--gtest_catch_exceptions=0` flag when running the tests. +When debugging the test failures, however, you may instead want the exceptions +to be handled by the debugger, such that you can examine the call stack when an +exception is thrown. To achieve that, set the `GTEST_CATCH_EXCEPTIONS` +environment variable to `0`, or use the `--gtest_catch_exceptions=0` flag when +running the tests. **Availability**: Linux, Windows, Mac. -### Letting Another Testing Framework Drive ### - -If you work on a project that has already been using another testing -framework and is not ready to completely switch to Google Test yet, -you can get much of Google Test's benefit by using its assertions in -your existing tests. Just change your `main()` function to look -like: - -``` -#include "gtest/gtest.h" - -int main(int argc, char** argv) { - ::testing::GTEST_FLAG(throw_on_failure) = true; - // Important: Google Test must be initialized. - ::testing::InitGoogleTest(&argc, argv); - - ... whatever your existing testing framework requires ... -} -``` - -With that, you can use Google Test assertions in addition to the -native assertions your testing framework provides, for example: - -``` -void TestFooDoesBar() { - Foo foo; - EXPECT_LE(foo.Bar(1), 100); // A Google Test assertion. - CPPUNIT_ASSERT(foo.IsEmpty()); // A native assertion. -} -``` - -If a Google Test assertion fails, it will print an error message and -throw an exception, which will be treated as a failure by your host -testing framework. If you compile your code with exceptions disabled, -a failed Google Test assertion will instead exit your program with a -non-zero code, which will also signal a test failure to your test -runner. - -If you don't write `::testing::GTEST_FLAG(throw_on_failure) = true;` in -your `main()`, you can alternatively enable this feature by specifying -the `--gtest_throw_on_failure` flag on the command-line or setting the -`GTEST_THROW_ON_FAILURE` environment variable to a non-zero value. - -Death tests are _not_ supported when other test framework is used to organize tests. - -_Availability:_ Linux, Windows, Mac; since v1.3.0. - -## Distributing Test Functions to Multiple Machines ## - -If you have more than one machine you can use to run a test program, -you might want to run the test functions in parallel and get the -result faster. We call this technique _sharding_, where each machine -is called a _shard_. - -Google Test is compatible with test sharding. To take advantage of -this feature, your test runner (not part of Google Test) needs to do -the following: - - 1. Allocate a number of machines (shards) to run the tests. - 1. On each shard, set the `GTEST_TOTAL_SHARDS` environment variable to the total number of shards. It must be the same for all shards. - 1. On each shard, set the `GTEST_SHARD_INDEX` environment variable to the index of the shard. Different shards must be assigned different indices, which must be in the range `[0, GTEST_TOTAL_SHARDS - 1]`. - 1. Run the same test program on all shards. When Google Test sees the above two environment variables, it will select a subset of the test functions to run. Across all shards, each test function in the program will be run exactly once. - 1. Wait for all shards to finish, then collect and report the results. - -Your project may have tests that were written without Google Test and -thus don't understand this protocol. In order for your test runner to -figure out which test supports sharding, it can set the environment -variable `GTEST_SHARD_STATUS_FILE` to a non-existent file path. If a -test program supports sharding, it will create this file to -acknowledge the fact (the actual contents of the file are not -important at this time; although we may stick some useful information -in it in the future.); otherwise it will not create it. - -Here's an example to make it clear. Suppose you have a test program -`foo_test` that contains the following 5 test functions: -``` -TEST(A, V) -TEST(A, W) -TEST(B, X) -TEST(B, Y) -TEST(B, Z) -``` -and you have 3 machines at your disposal. To run the test functions in -parallel, you would set `GTEST_TOTAL_SHARDS` to 3 on all machines, and -set `GTEST_SHARD_INDEX` to 0, 1, and 2 on the machines respectively. -Then you would run the same `foo_test` on each machine. - -Google Test reserves the right to change how the work is distributed -across the shards, but here's one possible scenario: - - * Machine #0 runs `A.V` and `B.X`. - * Machine #1 runs `A.W` and `B.Y`. - * Machine #2 runs `B.Z`. - -_Availability:_ Linux, Windows, Mac; since version 1.3.0. - -# Fusing Google Test Source Files # - -Google Test's implementation consists of ~30 files (excluding its own -tests). Sometimes you may want them to be packaged up in two files (a -`.h` and a `.cc`) instead, such that you can easily copy them to a new -machine and start hacking there. For this we provide an experimental -Python script `fuse_gtest_files.py` in the `scripts/` directory (since release 1.3.0). -Assuming you have Python 2.4 or above installed on your machine, just -go to that directory and run -``` -python fuse_gtest_files.py OUTPUT_DIR -``` - -and you should see an `OUTPUT_DIR` directory being created with files -`gtest/gtest.h` and `gtest/gtest-all.cc` in it. These files contain -everything you need to use Google Test. Just copy them to anywhere -you want and you are ready to write tests. You can use the -[scripts/test/Makefile](../scripts/test/Makefile) -file as an example on how to compile your tests against them. - -# Where to Go from Here # - -Congratulations! You've now learned more advanced Google Test tools and are -ready to tackle more complex testing tasks. If you want to dive even deeper, you -can read the [Frequently-Asked Questions](faq.md). diff --git a/googletest/docs/faq.md b/googletest/docs/faq.md index 1e2c3410..dad28369 100644 --- a/googletest/docs/faq.md +++ b/googletest/docs/faq.md @@ -1,337 +1,203 @@ +# Googletest FAQ -If you cannot find the answer to your question here, and you have read -[Primer](primer.md) and [AdvancedGuide](advanced.md), send it to -googletestframework@googlegroups.com. +## Why should test case names and test names not contain underscore? -## Why should I use Google Test instead of my favorite C++ testing framework? ## +Underscore (`_`) is special, as C++ reserves the following to be used by the +compiler and the standard library: -First, let us say clearly that we don't want to get into the debate of -which C++ testing framework is **the best**. There exist many fine -frameworks for writing C++ tests, and we have tremendous respect for -the developers and users of them. We don't think there is (or will -be) a single best framework - you have to pick the right tool for the -particular task you are tackling. +1. any identifier that starts with an `_` followed by an upper-case letter, and +1. any identifier that contains two consecutive underscores (i.e. `__`) + *anywhere* in its name. -We created Google Test because we couldn't find the right combination -of features and conveniences in an existing framework to satisfy _our_ -needs. The following is a list of things that _we_ like about Google -Test. We don't claim them to be unique to Google Test - rather, the -combination of them makes Google Test the choice for us. We hope this -list can help you decide whether it is for you too. - - * Google Test is designed to be portable: it doesn't require exceptions or RTTI; it works around various bugs in various compilers and environments; etc. As a result, it works on Linux, Mac OS X, Windows and several embedded operating systems. - * Nonfatal assertions (`EXPECT_*`) have proven to be great time savers, as they allow a test to report multiple failures in a single edit-compile-test cycle. - * It's easy to write assertions that generate informative messages: you just use the stream syntax to append any additional information, e.g. `ASSERT_EQ(5, Foo(i)) << " where i = " << i;`. It doesn't require a new set of macros or special functions. - * Google Test automatically detects your tests and doesn't require you to enumerate them in order to run them. - * Death tests are pretty handy for ensuring that your asserts in production code are triggered by the right conditions. - * `SCOPED_TRACE` helps you understand the context of an assertion failure when it comes from inside a sub-routine or loop. - * You can decide which tests to run using name patterns. This saves time when you want to quickly reproduce a test failure. - * Google Test can generate XML test result reports that can be parsed by popular continuous build system like Hudson. - * Simple things are easy in Google Test, while hard things are possible: in addition to advanced features like [global test environments](advanced.md#global-set-up-and-tear-down) and tests parameterized by [values](advanced.md#value-parameterized-tests) or [types](docs/advanced.md#typed-tests), Google Test supports various ways for the user to extend the framework -- if Google Test doesn't do something out of the box, chances are that a user can implement the feature using Google Test's public API, without changing Google Test itself. In particular, you can: - * expand your testing vocabulary by defining [custom predicates](advanced.md#predicate-assertions-for-better-error-messages), - * teach Google Test how to [print your types](advanced.md#teaching-google-test-how-to-print-your-values), - * define your own testing macros or utilities and verify them using Google Test's [Service Provider Interface](advanced.md#catching-failures), and - * reflect on the test cases or change the test output format by intercepting the [test events](advanced.md#extending-google-test-by-handling-test-events). - -## I'm getting warnings when compiling Google Test. Would you fix them? ## - -We strive to minimize compiler warnings Google Test generates. Before releasing a new version, we test to make sure that it doesn't generate warnings when compiled using its CMake script on Windows, Linux, and Mac OS. - -Unfortunately, this doesn't mean you are guaranteed to see no warnings when compiling Google Test in your environment: - - * You may be using a different compiler as we use, or a different version of the same compiler. We cannot possibly test for all compilers. - * You may be compiling on a different platform as we do. - * Your project may be using different compiler flags as we do. - -It is not always possible to make Google Test warning-free for everyone. Or, it may not be desirable if the warning is rarely enabled and fixing the violations makes the code more complex. - -If you see warnings when compiling Google Test, we suggest that you use the `-isystem` flag (assuming your are using GCC) to mark Google Test headers as system headers. That'll suppress warnings from Google Test headers. - -## Why should not test case names and test names contain underscore? ## - -Underscore (`_`) is special, as C++ reserves the following to be used by -the compiler and the standard library: - - 1. any identifier that starts with an `_` followed by an upper-case letter, and - 1. any identifier that contains two consecutive underscores (i.e. `__`) _anywhere_ in its name. - -User code is _prohibited_ from using such identifiers. +User code is *prohibited* from using such identifiers. Now let's look at what this means for `TEST` and `TEST_F`. Currently `TEST(TestCaseName, TestName)` generates a class named -`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName` +`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName` contains `_`? - 1. If `TestCaseName` starts with an `_` followed by an upper-case letter (say, `_Foo`), we end up with `_Foo_TestName_Test`, which is reserved and thus invalid. - 1. If `TestCaseName` ends with an `_` (say, `Foo_`), we get `Foo__TestName_Test`, which is invalid. - 1. If `TestName` starts with an `_` (say, `_Bar`), we get `TestCaseName__Bar_Test`, which is invalid. - 1. If `TestName` ends with an `_` (say, `Bar_`), we get `TestCaseName_Bar__Test`, which is invalid. +1. If `TestCaseName` starts with an `_` followed by an upper-case letter (say, + `_Foo`), we end up with `_Foo_TestName_Test`, which is reserved and thus + invalid. +1. If `TestCaseName` ends with an `_` (say, `Foo_`), we get + `Foo__TestName_Test`, which is invalid. +1. If `TestName` starts with an `_` (say, `_Bar`), we get + `TestCaseName__Bar_Test`, which is invalid. +1. If `TestName` ends with an `_` (say, `Bar_`), we get + `TestCaseName_Bar__Test`, which is invalid. -So clearly `TestCaseName` and `TestName` cannot start or end with `_` -(Actually, `TestCaseName` can start with `_` -- as long as the `_` isn't -followed by an upper-case letter. But that's getting complicated. So -for simplicity we just say that it cannot start with `_`.). +So clearly `TestCaseName` and `TestName` cannot start or end with `_` (Actually, +`TestCaseName` can start with `_` -- as long as the `_` isn't followed by an +upper-case letter. But that's getting complicated. So for simplicity we just say +that it cannot start with `_`.). + +It may seem fine for `TestCaseName` and `TestName` to contain `_` in the middle. +However, consider this: -It may seem fine for `TestCaseName` and `TestName` to contain `_` in the -middle. However, consider this: ```c++ TEST(Time, Flies_Like_An_Arrow) { ... } TEST(Time_Flies, Like_An_Arrow) { ... } ``` Now, the two `TEST`s will both generate the same class -(`Time_Files_Like_An_Arrow_Test`). That's not good. +(`Time_Flies_Like_An_Arrow_Test`). That's not good. -So for simplicity, we just ask the users to avoid `_` in `TestCaseName` -and `TestName`. The rule is more constraining than necessary, but it's -simple and easy to remember. It also gives Google Test some wiggle -room in case its implementation needs to change in the future. +So for simplicity, we just ask the users to avoid `_` in `TestCaseName` and +`TestName`. The rule is more constraining than necessary, but it's simple and +easy to remember. It also gives googletest some wiggle room in case its +implementation needs to change in the future. -If you violate the rule, there may not be immediately consequences, -but your test may (just may) break with a new compiler (or a new -version of the compiler you are using) or with a new version of Google -Test. Therefore it's best to follow the rule. +If you violate the rule, there may not be immediate consequences, but your test +may (just may) break with a new compiler (or a new version of the compiler you +are using) or with a new version of googletest. Therefore it's best to follow +the rule. -## Why is it not recommended to install a pre-compiled copy of Google Test (for example, into /usr/local)? ## +## Why does googletest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`? -In the early days, we said that you could install -compiled Google Test libraries on `*`nix systems using `make install`. -Then every user of your machine can write tests without -recompiling Google Test. +First of all you can use `EXPECT_NE(nullptr, ptr)` and `ASSERT_NE(nullptr, +ptr)`. This is the preferred syntax in the style guide because nullptr does not +have the type problems that NULL does. Which is why NULL does not work. -This seemed like a good idea, but it has a -got-cha: every user needs to compile their tests using the _same_ compiler -flags used to compile the installed Google Test libraries; otherwise -they may run into undefined behaviors (i.e. the tests can behave -strangely and may even crash for no obvious reasons). +Due to some peculiarity of C++, it requires some non-trivial template meta +programming tricks to support using `NULL` as an argument of the `EXPECT_XX()` +and `ASSERT_XX()` macros. Therefore we only do it where it's most needed +(otherwise we make the implementation of googletest harder to maintain and more +error-prone than necessary). -Why? Because C++ has this thing called the One-Definition Rule: if -two C++ source files contain different definitions of the same -class/function/variable, and you link them together, you violate the -rule. The linker may or may not catch the error (in many cases it's -not required by the C++ standard to catch the violation). If it -doesn't, you get strange run-time behaviors that are unexpected and -hard to debug. +The `EXPECT_EQ()` macro takes the *expected* value as its first argument and the +*actual* value as the second. It's reasonable that someone wants to write +`EXPECT_EQ(NULL, some_expression)`, and this indeed was requested several times. +Therefore we implemented it. -If you compile Google Test and your test code using different compiler -flags, they may see different definitions of the same -class/function/variable (e.g. due to the use of `#if` in Google Test). -Therefore, for your sanity, we recommend to avoid installing pre-compiled -Google Test libraries. Instead, each project should compile -Google Test itself such that it can be sure that the same flags are -used for both Google Test and the tests. +The need for `EXPECT_NE(NULL, ptr)` isn't nearly as strong. When the assertion +fails, you already know that `ptr` must be `NULL`, so it doesn't add any +information to print `ptr` in this case. That means `EXPECT_TRUE(ptr != NULL)` +works just as well. -## How do I generate 64-bit binaries on Windows (using Visual Studio 2008)? ## +If we were to support `EXPECT_NE(NULL, ptr)`, for consistency we'll have to +support `EXPECT_NE(ptr, NULL)` as well, as unlike `EXPECT_EQ`, we don't have a +convention on the order of the two arguments for `EXPECT_NE`. This means using +the template meta programming tricks twice in the implementation, making it even +harder to understand and maintain. We believe the benefit doesn't justify the +cost. -(Answered by Trevor Robinson) - -Load the supplied Visual Studio solution file, either `msvc\gtest-md.sln` or -`msvc\gtest.sln`. Go through the migration wizard to migrate the -solution and project files to Visual Studio 2008. Select -`Configuration Manager...` from the `Build` menu. Select `` from -the `Active solution platform` dropdown. Select `x64` from the new -platform dropdown, leave `Copy settings from` set to `Win32` and -`Create new project platforms` checked, then click `OK`. You now have -`Win32` and `x64` platform configurations, selectable from the -`Standard` toolbar, which allow you to toggle between building 32-bit or -64-bit binaries (or both at once using Batch Build). - -In order to prevent build output files from overwriting one another, -you'll need to change the `Intermediate Directory` settings for the -newly created platform configuration across all the projects. To do -this, multi-select (e.g. using shift-click) all projects (but not the -solution) in the `Solution Explorer`. Right-click one of them and -select `Properties`. In the left pane, select `Configuration Properties`, -and from the `Configuration` dropdown, select `All Configurations`. -Make sure the selected platform is `x64`. For the -`Intermediate Directory` setting, change the value from -`$(PlatformName)\$(ConfigurationName)` to -`$(OutDir)\$(ProjectName)`. Click `OK` and then build the -solution. When the build is complete, the 64-bit binaries will be in -the `msvc\x64\Debug` directory. - -## Can I use Google Test on MinGW? ## - -We haven't tested this ourselves, but Per Abrahamsen reported that he -was able to compile and install Google Test successfully when using -MinGW from Cygwin. You'll need to configure it with: - -`PATH/TO/configure CC="gcc -mno-cygwin" CXX="g++ -mno-cygwin"` - -You should be able to replace the `-mno-cygwin` option with direct links -to the real MinGW binaries, but we haven't tried that. - -Caveats: - - * There are many warnings when compiling. - * `make check` will produce some errors as not all tests for Google Test itself are compatible with MinGW. - -We also have reports on successful cross compilation of Google Test -MinGW binaries on Linux using -[these instructions](http://wiki.wxwidgets.org/Cross-Compiling_Under_Linux#Cross-compiling_under_Linux_for_MS_Windows) -on the WxWidgets site. - -Please contact `googletestframework@googlegroups.com` if you are -interested in improving the support for MinGW. - -## Why does Google Test support EXPECT\_EQ(NULL, ptr) and ASSERT\_EQ(NULL, ptr) but not EXPECT\_NE(NULL, ptr) and ASSERT\_NE(NULL, ptr)? ## - -Due to some peculiarity of C++, it requires some non-trivial template -meta programming tricks to support using `NULL` as an argument of the -`EXPECT_XX()` and `ASSERT_XX()` macros. Therefore we only do it where -it's most needed (otherwise we make the implementation of Google Test -harder to maintain and more error-prone than necessary). - -The `EXPECT_EQ()` macro takes the _expected_ value as its first -argument and the _actual_ value as the second. It's reasonable that -someone wants to write `EXPECT_EQ(NULL, some_expression)`, and this -indeed was requested several times. Therefore we implemented it. - -The need for `EXPECT_NE(NULL, ptr)` isn't nearly as strong. When the -assertion fails, you already know that `ptr` must be `NULL`, so it -doesn't add any information to print ptr in this case. That means -`EXPECT_TRUE(ptr != NULL)` works just as well. - -If we were to support `EXPECT_NE(NULL, ptr)`, for consistency we'll -have to support `EXPECT_NE(ptr, NULL)` as well, as unlike `EXPECT_EQ`, -we don't have a convention on the order of the two arguments for -`EXPECT_NE`. This means using the template meta programming tricks -twice in the implementation, making it even harder to understand and -maintain. We believe the benefit doesn't justify the cost. - -Finally, with the growth of Google Mock's [matcher](../../googlemock/docs/CookBook.md#using-matchers-in-google-test-assertions) library, we are -encouraging people to use the unified `EXPECT_THAT(value, matcher)` -syntax more often in tests. One significant advantage of the matcher -approach is that matchers can be easily combined to form new matchers, -while the `EXPECT_NE`, etc, macros cannot be easily -combined. Therefore we want to invest more in the matchers than in the +Finally, with the growth of the gMock matcher library, we are encouraging people +to use the unified `EXPECT_THAT(value, matcher)` syntax more often in tests. One +significant advantage of the matcher approach is that matchers can be easily +combined to form new matchers, while the `EXPECT_NE`, etc, macros cannot be +easily combined. Therefore we want to invest more in the matchers than in the `EXPECT_XX()` macros. -## Does Google Test support running tests in parallel? ## +## I need to test that different implementations of an interface satisfy some common requirements. Should I use typed tests or value-parameterized tests? -Test runners tend to be tightly coupled with the build/test -environment, and Google Test doesn't try to solve the problem of -running tests in parallel. Instead, we tried to make Google Test work -nicely with test runners. For example, Google Test's XML report -contains the time spent on each test, and its `gtest_list_tests` and -`gtest_filter` flags can be used for splitting the execution of test -methods into multiple processes. These functionalities can help the -test runner run the tests in parallel. +For testing various implementations of the same interface, either typed tests or +value-parameterized tests can get it done. It's really up to you the user to +decide which is more convenient for you, depending on your particular case. Some +rough guidelines: -## Why don't Google Test run the tests in different threads to speed things up? ## +* Typed tests can be easier to write if instances of the different + implementations can be created the same way, modulo the type. For example, + if all these implementations have a public default constructor (such that + you can write `new TypeParam`), or if their factory functions have the same + form (e.g. `CreateInstance()`). +* Value-parameterized tests can be easier to write if you need different code + patterns to create different implementations' instances, e.g. `new Foo` vs + `new Bar(5)`. To accommodate for the differences, you can write factory + function wrappers and pass these function pointers to the tests as their + parameters. +* When a typed test fails, the output includes the name of the type, which can + help you quickly identify which implementation is wrong. Value-parameterized + tests cannot do this, so there you'll have to look at the iteration number + to know which implementation the failure is from, which is less direct. +* If you make a mistake writing a typed test, the compiler errors can be + harder to digest, as the code is templatized. +* When using typed tests, you need to make sure you are testing against the + interface type, not the concrete types (in other words, you want to make + sure `implicit_cast(my_concrete_impl)` works, not just that + `my_concrete_impl` works). It's less likely to make mistakes in this area + when using value-parameterized tests. -It's difficult to write thread-safe code. Most tests are not written -with thread-safety in mind, and thus may not work correctly in a -multi-threaded setting. +I hope I didn't confuse you more. :-) If you don't mind, I'd suggest you to give +both approaches a try. Practice is a much better way to grasp the subtle +differences between the two tools. Once you have some concrete experience, you +can much more easily decide which one to use the next time. -If you think about it, it's already hard to make your code work when -you know what other threads are doing. It's much harder, and -sometimes even impossible, to make your code work when you don't know -what other threads are doing (remember that test methods can be added, -deleted, or modified after your test was written). If you want to run -the tests in parallel, you'd better run them in different processes. +## My death tests became very slow - what happened? -## Why aren't Google Test assertions implemented using exceptions? ## +In August 2008 we had to switch the default death test style from `fast` to +`threadsafe`, as the former is no longer safe now that threaded logging is the +default. This caused many death tests to slow down. Unfortunately this change +was necessary. -Our original motivation was to be able to use Google Test in projects -that disable exceptions. Later we realized some additional benefits -of this approach: +Please read [Fixing Failing Death Tests](death_test_styles.md) for what you can +do. + +## I got some run-time errors about invalid proto descriptors when using `ProtocolMessageEquals`. Help! + +**Note:** `ProtocolMessageEquals` and `ProtocolMessageEquiv` are *deprecated* +now. Please use `EqualsProto`, etc instead. + +`ProtocolMessageEquals` and `ProtocolMessageEquiv` were redefined recently and +are now less tolerant on invalid protocol buffer definitions. In particular, if +you have a `foo.proto` that doesn't fully qualify the type of a protocol message +it references (e.g. `message` where it should be `message`), you +will now get run-time errors like: - 1. Throwing in a destructor is undefined behavior in C++. Not using exceptions means Google Test's assertions are safe to use in destructors. - 1. The `EXPECT_*` family of macros will continue even after a failure, allowing multiple failures in a `TEST` to be reported in a single run. This is a popular feature, as in C++ the edit-compile-test cycle is usually quite long and being able to fixing more than one thing at a time is a blessing. - 1. If assertions are implemented using exceptions, a test may falsely ignore a failure if it's caught by user code: -```c++ -try { ... ASSERT_TRUE(...) ... } -catch (...) { ... } ``` -The above code will pass even if the `ASSERT_TRUE` throws. While it's unlikely for someone to write this in a test, it's possible to run into this pattern when you write assertions in callbacks that are called by the code under test. - -The downside of not using exceptions is that `ASSERT_*` (implemented -using `return`) will only abort the current function, not the current -`TEST`. - -## Why do we use two different macros for tests with and without fixtures? ## - -Unfortunately, C++'s macro system doesn't allow us to use the same -macro for both cases. One possibility is to provide only one macro -for tests with fixtures, and require the user to define an empty -fixture sometimes: - -```c++ -class FooTest : public ::testing::Test {}; - -TEST_F(FooTest, DoesThis) { ... } -``` -or -```c++ -typedef ::testing::Test FooTest; - -TEST_F(FooTest, DoesThat) { ... } +... descriptor.cc:...] Invalid proto descriptor for file "path/to/foo.proto": +... descriptor.cc:...] blah.MyMessage.my_field: ".Bar" is not defined. ``` -Yet, many people think this is one line too many. :-) Our goal was to -make it really easy to write tests, so we tried to make simple tests -trivial to create. That means using a separate macro for such tests. +If you see this, your `.proto` file is broken and needs to be fixed by making +the types fully qualified. The new definition of `ProtocolMessageEquals` and +`ProtocolMessageEquiv` just happen to reveal your bug. -We think neither approach is ideal, yet either of them is reasonable. -In the end, it probably doesn't matter much either way. - -## Why don't we use structs as test fixtures? ## - -We like to use structs only when representing passive data. This -distinction between structs and classes is good for documenting the -intent of the code's author. Since test fixtures have logic like -`SetUp()` and `TearDown()`, they are better defined as classes. - -## Why are death tests implemented as assertions instead of using a test runner? ## - -Our goal was to make death tests as convenient for a user as C++ -possibly allows. In particular: - - * The runner-style requires to split the information into two pieces: the definition of the death test itself, and the specification for the runner on how to run the death test and what to expect. The death test would be written in C++, while the runner spec may or may not be. A user needs to carefully keep the two in sync. `ASSERT_DEATH(statement, expected_message)` specifies all necessary information in one place, in one language, without boilerplate code. It is very declarative. - * `ASSERT_DEATH` has a similar syntax and error-reporting semantics as other Google Test assertions, and thus is easy to learn. - * `ASSERT_DEATH` can be mixed with other assertions and other logic at your will. You are not limited to one death test per test method. For example, you can write something like: -```c++ - if (FooCondition()) { - ASSERT_DEATH(Bar(), "blah"); - } else { - ASSERT_EQ(5, Bar()); - } -``` -If you prefer one death test per test method, you can write your tests in that style too, but we don't want to impose that on the users. The fewer artificial limitations the better. - * `ASSERT_DEATH` can reference local variables in the current function, and you can decide how many death tests you want based on run-time information. For example, -```c++ - const int count = GetCount(); // Only known at run time. - for (int i = 1; i <= count; i++) { - ASSERT_DEATH({ - double* buffer = new double[i]; - ... initializes buffer ... - Foo(buffer, i) - }, "blah blah"); - } -``` -The runner-based approach tends to be more static and less flexible, or requires more user effort to get this kind of flexibility. - -Another interesting thing about `ASSERT_DEATH` is that it calls `fork()` -to create a child process to run the death test. This is lightening -fast, as `fork()` uses copy-on-write pages and incurs almost zero -overhead, and the child process starts from the user-supplied -statement directly, skipping all global and local initialization and -any code leading to the given statement. If you launch the child -process from scratch, it can take seconds just to load everything and -start running if the test links to many libraries dynamically. - -## My death test modifies some state, but the change seems lost after the death test finishes. Why? ## +## My death test modifies some state, but the change seems lost after the death test finishes. Why? Death tests (`EXPECT_DEATH`, etc) are executed in a sub-process s.t. the expected crash won't kill the test program (i.e. the parent process). As a -result, any in-memory side effects they incur are observable in their -respective sub-processes, but not in the parent process. You can think of them -as running in a parallel universe, more or less. +result, any in-memory side effects they incur are observable in their respective +sub-processes, but not in the parent process. You can think of them as running +in a parallel universe, more or less. -## The compiler complains about "undefined references" to some static const member variables, but I did define them in the class body. What's wrong? ## +In particular, if you use [gMock](http://go/gmock) and the death test statement +invokes some mock methods, the parent process will think the calls have never +occurred. Therefore, you may want to move your `EXPECT_CALL` statements inside +the `EXPECT_DEATH` macro. + +## EXPECT_EQ(htonl(blah), blah_blah) generates weird compiler errors in opt mode. Is this a googletest bug? + +Actually, the bug is in `htonl()`. + +According to `'man htonl'`, `htonl()` is a *function*, which means it's valid to +use `htonl` as a function pointer. However, in opt mode `htonl()` is defined as +a *macro*, which breaks this usage. + +Worse, the macro definition of `htonl()` uses a `gcc` extension and is *not* +standard C++. That hacky implementation has some ad hoc limitations. In +particular, it prevents you from writing `Foo()`, where `Foo` +is a template that has an integral argument. + +The implementation of `EXPECT_EQ(a, b)` uses `sizeof(... a ...)` inside a +template argument, and thus doesn't compile in opt mode when `a` contains a call +to `htonl()`. It is difficult to make `EXPECT_EQ` bypass the `htonl()` bug, as +the solution must work with different compilers on various platforms. + +`htonl()` has some other problems as described in `//util/endian/endian.h`, +which defines `ghtonl()` to replace it. `ghtonl()` does the same thing `htonl()` +does, only without its problems. We suggest you to use `ghtonl()` instead of +`htonl()`, both in your tests and production code. + +`//util/endian/endian.h` also defines `ghtons()`, which solves similar problems +in `htons()`. + +Don't forget to add `//util/endian` to the list of dependencies in the `BUILD` +file wherever `ghtonl()` and `ghtons()` are used. The library consists of a +single header file and will not bloat your binary. + +## The compiler complains about "undefined references" to some static const member variables, but I did define them in the class body. What's wrong? If your class has a static data member: @@ -343,23 +209,18 @@ class Foo { }; ``` -You also need to define it _outside_ of the class body in `foo.cc`: +You also need to define it *outside* of the class body in `foo.cc`: ```c++ const int Foo::kBar; // No initializer here. ``` Otherwise your code is **invalid C++**, and may break in unexpected ways. In -particular, using it in Google Test comparison assertions (`EXPECT_EQ`, etc) -will generate an "undefined reference" linker error. +particular, using it in googletest comparison assertions (`EXPECT_EQ`, etc) will +generate an "undefined reference" linker error. The fact that "it used to work" +doesn't mean it's valid. It just means that you were lucky. :-) -## I have an interface that has several implementations. Can I write a set of tests once and repeat them over all the implementations? ## - -Google Test doesn't yet have good support for this kind of tests, or -data-driven tests in general. We hope to be able to make improvements in this -area soon. - -## Can I derive a test fixture from another? ## +## Can I derive a test fixture from another? Yes. @@ -369,33 +230,35 @@ cases may want to use the same or slightly different fixtures. For example, you may want to make sure that all of a GUI library's test cases don't leak important system resources like fonts and brushes. -In Google Test, you share a fixture among test cases by putting the shared -logic in a base test fixture, then deriving from that base a separate fixture -for each test case that wants to use this common logic. You then use `TEST_F()` -to write tests using each derived fixture. +In googletest, you share a fixture among test cases by putting the shared logic +in a base test fixture, then deriving from that base a separate fixture for each +test case that wants to use this common logic. You then use `TEST_F()` to write +tests using each derived fixture. Typically, your code looks like this: ```c++ // Defines a base test fixture. class BaseTest : public ::testing::Test { - protected: - ... + protected: + ... }; // Derives a fixture FooTest from BaseTest. class FooTest : public BaseTest { - protected: - virtual void SetUp() { - BaseTest::SetUp(); // Sets up the base fixture first. - ... additional set-up work ... - } - virtual void TearDown() { - ... clean-up work for FooTest ... - BaseTest::TearDown(); // Remember to tear down the base fixture - // after cleaning up FooTest! - } - ... functions and variables for FooTest ... + protected: + void SetUp() override { + BaseTest::SetUp(); // Sets up the base fixture first. + ... additional set-up work ... + } + + void TearDown() override { + ... clean-up work for FooTest ... + BaseTest::TearDown(); // Remember to tear down the base fixture + // after cleaning up FooTest! + } + + ... functions and variables for FooTest ... }; // Tests that use the fixture FooTest. @@ -406,32 +269,35 @@ TEST_F(FooTest, Baz) { ... } ``` If necessary, you can continue to derive test fixtures from a derived fixture. -Google Test has no limit on how deep the hierarchy can be. +googletest has no limit on how deep the hierarchy can be. -For a complete example using derived test fixtures, see -[sample5](../samples/sample5_unittest.cc). +For a complete example using derived test fixtures, see [googletest +sample](https://github.com/google/googletest/blob/master/googletest/samples/sample5_unittest.cc) -## My compiler complains "void value not ignored as it ought to be." What does this mean? ## +## My compiler complains "void value not ignored as it ought to be." What does this mean? You're probably using an `ASSERT_*()` in a function that doesn't return `void`. -`ASSERT_*()` can only be used in `void` functions. +`ASSERT_*()` can only be used in `void` functions, due to exceptions being +disabled by our build system. Please see more details +[here](advanced.md#assertion-placement). -## My death test hangs (or seg-faults). How do I fix it? ## +## My death test hangs (or seg-faults). How do I fix it? -In Google Test, death tests are run in a child process and the way they work is +In googletest, death tests are run in a child process and the way they work is delicate. To write death tests you really need to understand how they work. -Please make sure you have read this. +Please make sure you have read [this](advanced.md#how-it-works). In particular, death tests don't like having multiple threads in the parent -process. So the first thing you can try is to eliminate creating threads -outside of `EXPECT_DEATH()`. +process. So the first thing you can try is to eliminate creating threads outside +of `EXPECT_DEATH()`. For example, you may want to use [mocks](http://go/gmock) +or fake objects instead of real ones in your tests. Sometimes this is impossible as some library you must use may be creating threads before `main()` is even reached. In this case, you can try to minimize the chance of conflicts by either moving as many activities as possible inside `EXPECT_DEATH()` (in the extreme case, you want to move everything inside), or -leaving as few things as possible in it. Also, you can try to set the death -test style to `"threadsafe"`, which is safer but slower, and see if it helps. +leaving as few things as possible in it. Also, you can try to set the death test +style to `"threadsafe"`, which is safer but slower, and see if it helps. If you go with thread-safe death tests, remember that they rerun the test program from the beginning in the child process. Therefore make sure your @@ -441,28 +307,52 @@ In the end, this boils down to good concurrent programming. You have to make sure that there is no race conditions or dead locks in your program. No silver bullet - sorry! -## Should I use the constructor/destructor of the test fixture or the set-up/tear-down function? ## +## Should I use the constructor/destructor of the test fixture or SetUp()/TearDown()? -The first thing to remember is that Google Test does not reuse the -same test fixture object across multiple tests. For each `TEST_F`, -Google Test will create a fresh test fixture object, _immediately_ -call `SetUp()`, run the test body, call `TearDown()`, and then -_immediately_ delete the test fixture object. +The first thing to remember is that googletest does **not** reuse the same test +fixture object across multiple tests. For each `TEST_F`, googletest will create +a **fresh** test fixture object, immediately call `SetUp()`, run the test body, +call `TearDown()`, and then delete the test fixture object. -When you need to write per-test set-up and tear-down logic, you have -the choice between using the test fixture constructor/destructor or -`SetUp()/TearDown()`. The former is usually preferred, as it has the -following benefits: +When you need to write per-test set-up and tear-down logic, you have the choice +between using the test fixture constructor/destructor or `SetUp()/TearDown()`. +The former is usually preferred, as it has the following benefits: - * By initializing a member variable in the constructor, we have the option to make it `const`, which helps prevent accidental changes to its value and makes the tests more obviously correct. - * In case we need to subclass the test fixture class, the subclass' constructor is guaranteed to call the base class' constructor first, and the subclass' destructor is guaranteed to call the base class' destructor afterward. With `SetUp()/TearDown()`, a subclass may make the mistake of forgetting to call the base class' `SetUp()/TearDown()` or call them at the wrong moment. +* By initializing a member variable in the constructor, we have the option to + make it `const`, which helps prevent accidental changes to its value and + makes the tests more obviously correct. +* In case we need to subclass the test fixture class, the subclass' + constructor is guaranteed to call the base class' constructor *first*, and + the subclass' destructor is guaranteed to call the base class' destructor + *afterward*. With `SetUp()/TearDown()`, a subclass may make the mistake of + forgetting to call the base class' `SetUp()/TearDown()` or call them at the + wrong time. You may still want to use `SetUp()/TearDown()` in the following rare cases: - * If the tear-down operation could throw an exception, you must use `TearDown()` as opposed to the destructor, as throwing in a destructor leads to undefined behavior and usually will kill your program right away. Note that many standard libraries (like STL) may throw when exceptions are enabled in the compiler. Therefore you should prefer `TearDown()` if you want to write portable tests that work with or without exceptions. - * The assertion macros throw an exception when flag `--gtest_throw_on_failure` is specified. Therefore, you shouldn't use Google Test assertions in a destructor if you plan to run your tests with this flag. - * In a constructor or destructor, you cannot make a virtual function call on this object. (You can call a method declared as virtual, but it will be statically bound.) Therefore, if you need to call a method that will be overridden in a derived class, you have to use `SetUp()/TearDown()`. -## The compiler complains "no matching function to call" when I use ASSERT\_PREDn. How do I fix it? ## +* In the body of a constructor (or destructor), it's not possible to use the + `ASSERT_xx` macros. Therefore, if the set-up operation could cause a fatal + test failure that should prevent the test from running, it's necessary to + use a `CHECK` macro or to use `SetUp()` instead of a constructor. +* If the tear-down operation could throw an exception, you must use + `TearDown()` as opposed to the destructor, as throwing in a destructor leads + to undefined behavior and usually will kill your program right away. Note + that many standard libraries (like STL) may throw when exceptions are + enabled in the compiler. Therefore you should prefer `TearDown()` if you + want to write portable tests that work with or without exceptions. +* The googletest team is considering making the assertion macros throw on + platforms where exceptions are enabled (e.g. Windows, Mac OS, and Linux + client-side), which will eliminate the need for the user to propagate + failures from a subroutine to its caller. Therefore, you shouldn't use + googletest assertions in a destructor if your code could run on such a + platform. +* In a constructor or destructor, you cannot make a virtual function call on + this object. (You can call a method declared as virtual, but it will be + statically bound.) Therefore, if you need to call a method that will be + overridden in a derived class, you have to use `SetUp()/TearDown()`. + + +## The compiler complains "no matching function to call" when I use ASSERT_PRED*. How do I fix it? If the predicate function you use in `ASSERT_PRED*` or `EXPECT_PRED*` is overloaded or a template, the compiler will have trouble figuring out which @@ -480,6 +370,7 @@ For example, suppose you have bool IsPositive(int n) { return n > 0; } + bool IsPositive(double x) { return x > 0; } @@ -497,8 +388,8 @@ However, this will work: EXPECT_PRED1(static_cast(IsPositive), 5); ``` -(The stuff inside the angled brackets for the `static_cast` operator is the -type of the function pointer for the `int`-version of `IsPositive()`.) +(The stuff inside the angled brackets for the `static_cast` operator is the type +of the function pointer for the `int`-version of `IsPositive()`.) As another example, when you have a template function @@ -522,72 +413,76 @@ following won't compile: ASSERT_PRED2(GreaterThan, 5, 0); ``` - -as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments, -which is one more than expected. The workaround is to wrap the predicate -function in parentheses: +as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments, which +is one more than expected. The workaround is to wrap the predicate function in +parentheses: ```c++ ASSERT_PRED2((GreaterThan), 5, 0); ``` -## My compiler complains about "ignoring return value" when I call RUN\_ALL\_TESTS(). Why? ## +## My compiler complains about "ignoring return value" when I call RUN_ALL_TESTS(). Why? Some people had been ignoring the return value of `RUN_ALL_TESTS()`. That is, instead of ```c++ -return RUN_ALL_TESTS(); + return RUN_ALL_TESTS(); ``` they write ```c++ -RUN_ALL_TESTS(); + RUN_ALL_TESTS(); ``` -This is wrong and dangerous. A test runner needs to see the return value of -`RUN_ALL_TESTS()` in order to determine if a test has passed. If your `main()` -function ignores it, your test will be considered successful even if it has a -Google Test assertion failure. Very bad. +This is **wrong and dangerous**. The testing services needs to see the return +value of `RUN_ALL_TESTS()` in order to determine if a test has passed. If your +`main()` function ignores it, your test will be considered successful even if it +has a googletest assertion failure. Very bad. -To help the users avoid this dangerous bug, the implementation of -`RUN_ALL_TESTS()` causes gcc to raise this warning, when the return value is -ignored. If you see this warning, the fix is simple: just make sure its value -is used as the return value of `main()`. +We have decided to fix this (thanks to Michael Chastain for the idea). Now, your +code will no longer be able to ignore `RUN_ALL_TESTS()` when compiled with +`gcc`. If you do so, you'll get a compiler error. -## My compiler complains that a constructor (or destructor) cannot return a value. What's going on? ## +If you see the compiler complaining about you ignoring the return value of +`RUN_ALL_TESTS()`, the fix is simple: just make sure its value is used as the +return value of `main()`. + +But how could we introduce a change that breaks existing tests? Well, in this +case, the code was already broken in the first place, so we didn't break it. :-) + +## My compiler complains that a constructor (or destructor) cannot return a value. What's going on? Due to a peculiarity of C++, in order to support the syntax for streaming messages to an `ASSERT_*`, e.g. ```c++ -ASSERT_EQ(1, Foo()) << "blah blah" << foo; + ASSERT_EQ(1, Foo()) << "blah blah" << foo; ``` we had to give up using `ASSERT*` and `FAIL*` (but not `EXPECT*` and `ADD_FAILURE*`) in constructors and destructors. The workaround is to move the content of your constructor/destructor to a private void member function, or -switch to `EXPECT_*()` if that works. This section in the user's guide explains -it. +switch to `EXPECT_*()` if that works. This +[section](advanced.md#assertion-placement) in the user's guide explains it. -## My set-up function is not called. Why? ## +## My SetUp() function is not called. Why? -C++ is case-sensitive. It should be spelled as `SetUp()`. Did you -spell it as `Setup()`? +C++ is case-sensitive. Did you spell it as `Setup()`? Similarly, sometimes people spell `SetUpTestCase()` as `SetupTestCase()` and wonder why it's never called. -## How do I jump to the line of a failure in Emacs directly? ## +## How do I jump to the line of a failure in Emacs directly? -Google Test's failure message format is understood by Emacs and many other -IDEs, like acme and XCode. If a Google Test message is in a compilation buffer -in Emacs, then it's clickable. You can now hit `enter` on a message to jump to -the corresponding source code, or use `C-x `` to jump to the next failure. +googletest's failure message format is understood by Emacs and many other IDEs, +like acme and XCode. If a googletest message is in a compilation buffer in +Emacs, then it's clickable. -## I have several test cases which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious. ## + +## I have several test cases which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious. You don't have to. Instead of @@ -604,6 +499,7 @@ TEST_F(BarTest, Def) { ... } ``` you can simply `typedef` the test fixtures: + ```c++ typedef BaseTest FooTest; @@ -616,192 +512,47 @@ TEST_F(BarTest, Abc) { ... } TEST_F(BarTest, Def) { ... } ``` -## The Google Test output is buried in a whole bunch of log messages. What do I do? ## +## googletest output is buried in a whole bunch of LOG messages. What do I do? -The Google Test output is meant to be a concise and human-friendly report. If -your test generates textual output itself, it will mix with the Google Test +The googletest output is meant to be a concise and human-friendly report. If +your test generates textual output itself, it will mix with the googletest output, making it hard to read. However, there is an easy solution to this problem. -Since most log messages go to stderr, we decided to let Google Test output go -to stdout. This way, you can easily separate the two using redirection. For +Since `LOG` messages go to stderr, we decided to let googletest output go to +stdout. This way, you can easily separate the two using redirection. For example: -``` -./my_test > googletest_output.txt + +```shell +$ ./my_test > gtest_output.txt ``` -## Why should I prefer test fixtures over global variables? ## + +## Why should I prefer test fixtures over global variables? There are several good reasons: - 1. It's likely your test needs to change the states of its global variables. This makes it difficult to keep side effects from escaping one test and contaminating others, making debugging difficult. By using fixtures, each test has a fresh set of variables that's different (but with the same names). Thus, tests are kept independent of each other. - 1. Global variables pollute the global namespace. - 1. Test fixtures can be reused via subclassing, which cannot be done easily with global variables. This is useful if many test cases have something in common. -## How do I test private class members without writing FRIEND\_TEST()s? ## - -You should try to write testable code, which means classes should be easily -tested from their public interface. One way to achieve this is the Pimpl idiom: -you move all private members of a class into a helper class, and make all -members of the helper class public. - -You have several other options that don't require using `FRIEND_TEST`: - * Write the tests as members of the fixture class: -```c++ -class Foo { - friend class FooTest; - ... -}; - -class FooTest : public ::testing::Test { - protected: - ... - void Test1() {...} // This accesses private members of class Foo. - void Test2() {...} // So does this one. -}; - -TEST_F(FooTest, Test1) { - Test1(); -} - -TEST_F(FooTest, Test2) { - Test2(); -} -``` - * In the fixture class, write accessors for the tested class' private members, then use the accessors in your tests: -```c++ -class Foo { - friend class FooTest; - ... -}; - -class FooTest : public ::testing::Test { - protected: - ... - T1 get_private_member1(Foo* obj) { - return obj->private_member1_; - } -}; - -TEST_F(FooTest, Test1) { - ... - get_private_member1(x) - ... -} -``` - * If the methods are declared **protected**, you can change their access level in a test-only subclass: -```c++ -class YourClass { - ... - protected: // protected access for testability. - int DoSomethingReturningInt(); - ... -}; - -// in the your_class_test.cc file: -class TestableYourClass : public YourClass { - ... - public: using YourClass::DoSomethingReturningInt; // changes access rights - ... -}; - -TEST_F(YourClassTest, DoSomethingTest) { - TestableYourClass obj; - assertEquals(expected_value, obj.DoSomethingReturningInt()); -} -``` - -## How do I test private class static members without writing FRIEND\_TEST()s? ## - -We find private static methods clutter the header file. They are -implementation details and ideally should be kept out of a .h. So often I make -them free functions instead. - -Instead of: -```c++ -// foo.h -class Foo { - ... - private: - static bool Func(int n); -}; - -// foo.cc -bool Foo::Func(int n) { ... } - -// foo_test.cc -EXPECT_TRUE(Foo::Func(12345)); -``` - -You probably should better write: -```c++ -// foo.h -class Foo { - ... -}; - -// foo.cc -namespace internal { - bool Func(int n) { ... } -} - -// foo_test.cc -namespace internal { - bool Func(int n); -} - -EXPECT_TRUE(internal::Func(12345)); -``` - -## I would like to run a test several times with different parameters. Do I need to write several similar copies of it? ## - -No. You can use a feature called [value-parameterized tests](advanced.md#Value_Parameterized_Tests) which -lets you repeat your tests with different parameters, without defining it more than once. - -## How do I test a file that defines main()? ## - -To test a `foo.cc` file, you need to compile and link it into your unit test -program. However, when the file contains a definition for the `main()` -function, it will clash with the `main()` of your unit test, and will result in -a build error. - -The right solution is to split it into three files: - 1. `foo.h` which contains the declarations, - 1. `foo.cc` which contains the definitions except `main()`, and - 1. `foo_main.cc` which contains nothing but the definition of `main()`. - -Then `foo.cc` can be easily tested. - -If you are adding tests to an existing file and don't want an intrusive change -like this, there is a hack: just include the entire `foo.cc` file in your unit -test. For example: -```c++ -// File foo_unittest.cc - -// The headers section -... - -// Renames main() in foo.cc to make room for the unit test main() -#define main FooMain - -#include "a/b/foo.cc" - -// The tests start here. -... -``` +1. It's likely your test needs to change the states of its global variables. + This makes it difficult to keep side effects from escaping one test and + contaminating others, making debugging difficult. By using fixtures, each + test has a fresh set of variables that's different (but with the same + names). Thus, tests are kept independent of each other. +1. Global variables pollute the global namespace. +1. Test fixtures can be reused via subclassing, which cannot be done easily + with global variables. This is useful if many test cases have something in + common. -However, please remember this is a hack and should only be used as the last -resort. + ## What can the statement argument in ASSERT_DEATH() be? -## What can the statement argument in ASSERT\_DEATH() be? ## - -`ASSERT_DEATH(_statement_, _regex_)` (or any death assertion macro) can be used -wherever `_statement_` is valid. So basically `_statement_` can be any C++ +`ASSERT_DEATH(*statement*, *regex*)` (or any death assertion macro) can be used +wherever `*statement*` is valid. So basically `*statement*` can be any C++ statement that makes sense in the current context. In particular, it can reference global and/or local variables, and can be: - * a simple function call (often the case), - * a complex expression, or - * a compound statement. + +* a simple function call (often the case), +* a complex expression, or +* a compound statement. Some examples are shown here: @@ -818,7 +569,7 @@ TEST(MyDeathTest, ComplexExpression) { "(Func1|Method) failed"); } -// Death assertions can be used any where in a function. In +// Death assertions can be used any where in a function. In // particular, they can be inside a loop. TEST(MyDeathTest, InsideLoop) { // Verifies that Foo(0), Foo(1), ..., and Foo(4) all die. @@ -837,49 +588,47 @@ TEST(MyDeathTest, CompoundStatement) { Bar(i); } }, - "Bar has \\d+ errors");} + "Bar has \\d+ errors"); +} ``` -`googletest_unittest.cc` contains more examples if you are interested. +gtest-death-test_test.cc contains more examples if you are interested. -## What syntax does the regular expression in ASSERT\_DEATH use? ## +## I have a fixture class `FooTest`, but `TEST_F(FooTest, Bar)` gives me error ``"no matching function for call to `FooTest::FooTest()'"``. Why? -On POSIX systems, Google Test uses the POSIX Extended regular -expression syntax -(http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions). -On Windows, it uses a limited variant of regular expression -syntax. For more details, see the -[regular expression syntax](advanced.md#Regular_Expression_Syntax). +Googletest needs to be able to create objects of your test fixture class, so it +must have a default constructor. Normally the compiler will define one for you. +However, there are cases where you have to define your own: -## I have a fixture class Foo, but TEST\_F(Foo, Bar) gives me error "no matching function for call to Foo::Foo()". Why? ## +* If you explicitly declare a non-default constructor for class `FooTest` + (`DISALLOW_EVIL_CONSTRUCTORS()` does this), then you need to define a + default constructor, even if it would be empty. +* If `FooTest` has a const non-static data member, then you have to define the + default constructor *and* initialize the const member in the initializer + list of the constructor. (Early versions of `gcc` doesn't force you to + initialize the const member. It's a bug that has been fixed in `gcc 4`.) -Google Test needs to be able to create objects of your test fixture class, so -it must have a default constructor. Normally the compiler will define one for -you. However, there are cases where you have to define your own: - * If you explicitly declare a non-default constructor for class `Foo`, then you need to define a default constructor, even if it would be empty. - * If `Foo` has a const non-static data member, then you have to define the default constructor _and_ initialize the const member in the initializer list of the constructor. (Early versions of `gcc` doesn't force you to initialize the const member. It's a bug that has been fixed in `gcc 4`.) +## Why does ASSERT_DEATH complain about previous threads that were already joined? -## Why does ASSERT\_DEATH complain about previous threads that were already joined? ## - -With the Linux pthread library, there is no turning back once you cross the -line from single thread to multiple threads. The first time you create a -thread, a manager thread is created in addition, so you get 3, not 2, threads. -Later when the thread you create joins the main thread, the thread count -decrements by 1, but the manager thread will never be killed, so you still have -2 threads, which means you cannot safely run a death test. +With the Linux pthread library, there is no turning back once you cross the line +from single thread to multiple threads. The first time you create a thread, a +manager thread is created in addition, so you get 3, not 2, threads. Later when +the thread you create joins the main thread, the thread count decrements by 1, +but the manager thread will never be killed, so you still have 2 threads, which +means you cannot safely run a death test. The new NPTL thread library doesn't suffer from this problem, as it doesn't create a manager thread. However, if you don't control which machine your test runs on, you shouldn't depend on this. -## Why does Google Test require the entire test case, instead of individual tests, to be named FOODeathTest when it uses ASSERT\_DEATH? ## +## Why does googletest require the entire test case, instead of individual tests, to be named *DeathTest when it uses ASSERT_DEATH? -Google Test does not interleave tests from different test cases. That is, it -runs all tests in one test case first, and then runs all tests in the next test -case, and so on. Google Test does this because it needs to set up a test case -before the first test in it is run, and tear it down afterwords. Splitting up -the test case would require multiple set-up and tear-down processes, which is -inefficient and makes the semantics unclean. +googletest does not interleave tests from different test cases. That is, it runs +all tests in one test case first, and then runs all tests in the next test case, +and so on. googletest does this because it needs to set up a test case before +the first test in it is run, and tear it down afterwords. Splitting up the test +case would require multiple set-up and tear-down processes, which is inefficient +and makes the semantics unclean. If we were to determine the order of tests based on test name instead of test case name, then we would have a problem with the following situation: @@ -897,7 +646,7 @@ interleave tests from different test cases, we need to run all tests in the `FooTest` case before running any test in the `BarTest` case. This contradicts with the requirement to run `BarTest.DefDeathTest` before `FooTest.Uvw`. -## But I don't like calling my entire test case FOODeathTest when it contains both death tests and non-death tests. What do I do? ## +## But I don't like calling my entire test case \*DeathTest when it contains both death tests and non-death tests. What do I do? You don't have to, but if you like, you may split up the test case into `FooTest` and `FooDeathTest`, where the names make it clear that they are @@ -909,119 +658,81 @@ class FooTest : public ::testing::Test { ... }; TEST_F(FooTest, Abc) { ... } TEST_F(FooTest, Def) { ... } -typedef FooTest FooDeathTest; +using FooDeathTest = FooTest; TEST_F(FooDeathTest, Uvw) { ... EXPECT_DEATH(...) ... } TEST_F(FooDeathTest, Xyz) { ... ASSERT_DEATH(...) ... } ``` -## The compiler complains about "no match for 'operator<<'" when I use an assertion. What gives? ## +## googletest prints the LOG messages in a death test's child process only when the test fails. How can I see the LOG messages when the death test succeeds? + +Printing the LOG messages generated by the statement inside `EXPECT_DEATH()` +makes it harder to search for real problems in the parent's log. Therefore, +googletest only prints them when the death test has failed. + +If you really need to see such LOG messages, a workaround is to temporarily +break the death test (e.g. by changing the regex pattern it is expected to +match). Admittedly, this is a hack. We'll consider a more permanent solution +after the fork-and-exec-style death tests are implemented. + +## The compiler complains about "no match for 'operator<<'" when I use an assertion. What gives? If you use a user-defined type `FooType` in an assertion, you must make sure there is an `std::ostream& operator<<(std::ostream&, const FooType&)` function defined such that we can print a value of `FooType`. In addition, if `FooType` is declared in a name space, the `<<` operator also -needs to be defined in the _same_ name space. +needs to be defined in the *same* name space. See go/totw/49 for details. -## How do I suppress the memory leak messages on Windows? ## +## How do I suppress the memory leak messages on Windows? -Since the statically initialized Google Test singleton requires allocations on +Since the statically initialized googletest singleton requires allocations on the heap, the Visual C++ memory leak detector will report memory leaks at the end of the program run. The easiest way to avoid this is to use the `_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any statically initialized heap objects. See MSDN for more details and additional heap check/debug routines. -## I am building my project with Google Test in Visual Studio and all I'm getting is a bunch of linker errors (or warnings). Help! ## -You may get a number of the following linker error or warnings if you -attempt to link your test project with the Google Test library when -your project and the are not built using the same compiler settings. +## How can my code detect if it is running in a test? - * LNK2005: symbol already defined in object - * LNK4217: locally defined symbol 'symbol' imported in function 'function' - * LNK4049: locally defined symbol 'symbol' imported +If you write code that sniffs whether it's running in a test and does different +things accordingly, you are leaking test-only logic into production code and +there is no easy way to ensure that the test-only code paths aren't run by +mistake in production. Such cleverness also leads to +[Heisenbugs](https://en.wikipedia.org/wiki/Heisenbug). Therefore we strongly +advise against the practice, and googletest doesn't provide a way to do it. -The Google Test project (gtest.vcproj) has the Runtime Library option -set to /MT (use multi-threaded static libraries, /MTd for debug). If -your project uses something else, for example /MD (use multi-threaded -DLLs, /MDd for debug), you need to change the setting in the Google -Test project to match your project's. +In general, the recommended way to cause the code to behave differently under +test is [Dependency Injection](http://go/dependency-injection). You can inject +different functionality from the test and from the production code. Since your +production code doesn't link in the for-test logic at all (the +[`testonly`](http://go/testonly) attribute for BUILD targets helps to ensure +that), there is no danger in accidentally running it. -To update this setting open the project properties in the Visual -Studio IDE then select the branch Configuration Properties | C/C++ | -Code Generation and change the option "Runtime Library". You may also try -using gtest-md.vcproj instead of gtest.vcproj. - -## I put my tests in a library and Google Test doesn't run them. What's happening? ## -Have you read a -[warning](primer.md#important-note-for-visual-c-users) on -the Google Test Primer page? - -## I want to use Google Test with Visual Studio but don't know where to start. ## -Many people are in your position and one of them posted his solution to our mailing list. - -## I am seeing compile errors mentioning std::type\_traits when I try to use Google Test on Solaris. ## -Google Test uses parts of the standard C++ library that SunStudio does not support. -Our users reported success using alternative implementations. Try running the build after running this command: - -`export CC=cc CXX=CC CXXFLAGS='-library=stlport4'` - -## How can my code detect if it is running in a test? ## - -If you write code that sniffs whether it's running in a test and does -different things accordingly, you are leaking test-only logic into -production code and there is no easy way to ensure that the test-only -code paths aren't run by mistake in production. Such cleverness also -leads to -[Heisenbugs](http://en.wikipedia.org/wiki/Unusual_software_bug#Heisenbug). -Therefore we strongly advise against the practice, and Google Test doesn't -provide a way to do it. - -In general, the recommended way to cause the code to behave -differently under test is [dependency injection](http://jamesshore.com/Blog/Dependency-Injection-Demystified.html). -You can inject different functionality from the test and from the -production code. Since your production code doesn't link in the -for-test logic at all, there is no danger in accidentally running it. - -However, if you _really_, _really_, _really_ have no choice, and if -you follow the rule of ending your test program names with `_test`, -you can use the _horrible_ hack of sniffing your executable name -(`argv[0]` in `main()`) to know whether the code is under test. - -## Google Test defines a macro that clashes with one defined by another library. How do I deal with that? ## - -In C++, macros don't obey namespaces. Therefore two libraries that -both define a macro of the same name will clash if you `#include` both -definitions. In case a Google Test macro clashes with another -library, you can force Google Test to rename its macro to avoid the -conflict. - -Specifically, if both Google Test and some other code define macro -`FOO`, you can add -``` - -DGTEST_DONT_DEFINE_FOO=1 -``` -to the compiler flags to tell Google Test to change the macro's name -from `FOO` to `GTEST_FOO`. For example, with `-DGTEST_DONT_DEFINE_TEST=1`, you'll need to write -```c++ - GTEST_TEST(SomeTest, DoesThis) { ... } -``` -instead of -```c++ - TEST(SomeTest, DoesThis) { ... } -``` -in order to define a test. - -Currently, the following `TEST`, `FAIL`, `SUCCEED`, and the basic comparison assertion macros can have . You can see the full list of covered macros [here](../include/gtest/gtest.h). More information can be found in the "Avoiding Macro Name Clashes" section of the README file. +However, if you *really*, *really*, *really* have no choice, and if you follow +the rule of ending your test program names with `_test`, you can use the +*horrible* hack of sniffing your executable name (`argv[0]` in `main()`) to know +whether the code is under test. -## Is it OK if I have two separate `TEST(Foo, Bar)` test methods defined in different namespaces? ## +## How do I temporarily disable a test? + +If you have a broken test that you cannot fix right away, you can add the +DISABLED_ prefix to its name. This will exclude it from execution. This is +better than commenting out the code or using #if 0, as disabled tests are still +compiled (and thus won't rot). + +To include disabled tests in test execution, just invoke the test program with +the --gtest_also_run_disabled_tests flag. + +## Is it OK if I have two separate `TEST(Foo, Bar)` test methods defined in different namespaces? Yes. -The rule is **all test methods in the same test case must use the same fixture class**. This means that the following is **allowed** because both tests use the same fixture class (`::testing::Test`). +The rule is **all test methods in the same test case must use the same fixture +class.** This means that the following is **allowed** because both tests use the +same fixture class (`::testing::Test`). ```c++ namespace foo { @@ -1037,7 +748,9 @@ TEST(CoolTest, DoSomething) { } // namespace bar ``` -However, the following code is **not allowed** and will produce a runtime error from Google Test because the test methods are using different test fixture classes with the same test case name. +However, the following code is **not allowed** and will produce a runtime error +from googletest because the test methods are using different test fixture +classes with the same test case name. ```c++ namespace foo { @@ -1054,39 +767,3 @@ TEST_F(CoolTest, DoSomething) { } } // namespace bar ``` - -## How do I build Google Testing Framework with Xcode 4? ## - -If you try to build Google Test's Xcode project with Xcode 4.0 or later, you may encounter an error message that looks like -"Missing SDK in target gtest\_framework: /Developer/SDKs/MacOSX10.4u.sdk". That means that Xcode does not support the SDK the project is targeting. See the Xcode section in the [README](../README.md) file on how to resolve this. - -## How do I easily discover the flags needed for GoogleTest? ## - -GoogleTest (and GoogleMock) now support discovering all necessary flags using pkg-config. -See the [pkg-config guide](Pkgconfig.md) on how you can easily discover all compiler and -linker flags using pkg-config. - -## My question is not covered in your FAQ! ## - -If you cannot find the answer to your question in this FAQ, there are -some other resources you can use: - - 1. read other [wiki pages](../docs), - 1. search the mailing list [archive](https://groups.google.com/forum/#!forum/googletestframework), - 1. ask it on [googletestframework@googlegroups.com](mailto:googletestframework@googlegroups.com) and someone will answer it (to prevent spam, we require you to join the [discussion group](http://groups.google.com/group/googletestframework) before you can post.). - -Please note that creating an issue in the -[issue tracker](https://github.com/google/googletest/issues) is _not_ -a good way to get your answer, as it is monitored infrequently by a -very small number of people. - -When asking a question, it's helpful to provide as much of the -following information as possible (people cannot help you if there's -not enough information in your question): - - * the version (or the commit hash if you check out from Git directly) of Google Test you use (Google Test is under active development, so it's possible that your problem has been solved in a later version), - * your operating system, - * the name and version of your compiler, - * the complete command line flags you give to your compiler, - * the complete compiler error messages (if the question is about compilation), - * the _actual_ code (ideally, a minimal but complete program) that has the problem you encounter. diff --git a/googletest/docs/primer.md b/googletest/docs/primer.md index 9949658a..b80418e6 100644 --- a/googletest/docs/primer.md +++ b/googletest/docs/primer.md @@ -1,5 +1,6 @@ # Googletest Primer + ## Introduction: Why googletest? *googletest* helps you write better C++ tests. @@ -436,6 +437,7 @@ When these tests run, the following happens: **Availability**: Linux, Windows, Mac. + ## Invoking the Tests `TEST()` and `TEST_F()` implicitly register their tests with googletest. So, @@ -544,6 +546,7 @@ int main(int argc, char **argv) { } ``` + The `::testing::InitGoogleTest()` function parses the command line for googletest flags, and removes all recognized flags. This allows the user to control a test program's behavior via various flags, which we'll cover in @@ -560,6 +563,7 @@ gtest\_main library and you are good to go. NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`. + ## Known Limitations * Google Test is designed to be thread-safe. The implementation is thread-safe