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googletest/docs/primer.md
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@ -1,27 +1,48 @@
# Googletest Primer
## Introduction: Why googletest?
# Introduction: Why Google C++ Testing Framework? #
*googletest* helps you write better C++ tests.
_Google C++ Testing Framework_ helps you write better C++ tests.
googletest is a testing framework developed by the [Testing
Technology](http://engdoc/eng/testing/TT/) team with Google's specific
requirements and constraints in mind. No matter whether you work on Linux,
Windows, or a Mac, if you write C++ code, googletest can help you. And it
supports *any* kind of tests, not just unit tests.
No matter whether you work on Linux, Windows, or a Mac, if you write C++ code,
Google Test can help you.
So what makes a good test, and how does googletest fit in? We believe:
So what makes a good test, and how does Google C++ Testing Framework fit in? We believe:
1. Tests should be _independent_ and _repeatable_. It's a pain to debug a test that succeeds or fails as a result of other tests. Google C++ Testing Framework isolates the tests by running each of them on a different object. When a test fails, Google C++ Testing Framework allows you to run it in isolation for quick debugging.
1. Tests should be well _organized_ and reflect the structure of the tested code. Google C++ Testing Framework groups related tests into test cases that can share data and subroutines. This common pattern is easy to recognize and makes tests easy to maintain. Such consistency is especially helpful when people switch projects and start to work on a new code base.
1. Tests should be _portable_ and _reusable_. The open-source community has a lot of code that is platform-neutral, its tests should also be platform-neutral. Google C++ Testing Framework works on different OSes, with different compilers (gcc, MSVC, and others), with or without exceptions, so Google C++ Testing Framework tests can easily work with a variety of configurations. (Note that the current release only contains build scripts for Linux - we are actively working on scripts for other platforms.)
1. When tests fail, they should provide as much _information_ about the problem as possible. Google C++ Testing Framework doesn't stop at the first test failure. Instead, it only stops the current test and continues with the next. You can also set up tests that report non-fatal failures after which the current test continues. Thus, you can detect and fix multiple bugs in a single run-edit-compile cycle.
1. The testing framework should liberate test writers from housekeeping chores and let them focus on the test _content_. Google C++ Testing Framework automatically keeps track of all tests defined, and doesn't require the user to enumerate them in order to run them.
1. Tests should be _fast_. With Google C++ Testing Framework, you can reuse shared resources across tests and pay for the set-up/tear-down only once, without making tests depend on each other.
1. Tests should be *independent* and *repeatable*. It's a pain to debug a test
that succeeds or fails as a result of other tests. googletest isolates the
tests by running each of them on a different object. When a test fails,
googletest allows you to run it in isolation for quick debugging.
1. Tests should be well *organized* and reflect the structure of the tested
code. googletest groups related tests into test cases that can share data
and subroutines. This common pattern is easy to recognize and makes tests
easy to maintain. Such consistency is especially helpful when people switch
projects and start to work on a new code base.
1. Tests should be *portable* and *reusable*. Google has a lot of code that is
platform-neutral, its tests should also be platform-neutral. googletest
works on different OSes, with different compilers (gcc, icc, and MSVC), with
or without exceptions, so googletest tests can easily work with a variety of
configurations.
1. When tests fail, they should provide as much *information* about the problem
as possible. googletest doesn't stop at the first test failure. Instead, it
only stops the current test and continues with the next. You can also set up
tests that report non-fatal failures after which the current test continues.
Thus, you can detect and fix multiple bugs in a single run-edit-compile
cycle.
1. The testing framework should liberate test writers from housekeeping chores
and let them focus on the test *content*. googletest automatically keeps
track of all tests defined, and doesn't require the user to enumerate them
in order to run them.
1. Tests should be *fast*. With googletest, you can reuse shared resources
across tests and pay for the set-up/tear-down only once, without making
tests depend on each other.
Since Google C++ Testing Framework is based on the popular xUnit
architecture, you'll feel right at home if you've used JUnit or PyUnit before.
If not, it will take you about 10 minutes to learn the basics and get started.
So let's go!
_Note:_ We sometimes refer to Google C++ Testing Framework informally
as _Google Test_.
Since googletest is based on the popular xUnit architecture, you'll feel right
at home if you've used JUnit or PyUnit before. If not, it will take you about 10
minutes to learn the basics and get started. So let's go!
# Beware of the nomenclature #
@ -29,104 +50,77 @@ _Note:_ There might be some confusion of idea due to different
definitions of the terms _Test_, _Test Case_ and _Test Suite_, so beware
of misunderstanding these.
Historically, the Google C++ Testing Framework started to use the term
_Test Case_ for grouping related tests, whereas current publications
including the International Software Testing Qualifications Board
([ISTQB](http://www.istqb.org/)) and various textbooks on Software
Quality use the term _[Test
Historically, googletest started to use the term _Test Case_ for grouping
related tests, whereas current publications including the International Software
Testing Qualifications Board ([ISTQB](http://www.istqb.org/)) and various
textbooks on Software Quality use the term _[Test
Suite](http://glossary.istqb.org/search/test%20suite)_ for this.
The related term _Test_, as it is used in the Google C++ Testing
Framework, is corresponding to the term _[Test
Case](http://glossary.istqb.org/search/test%20case)_ of ISTQB and
others.
The related term _Test_, as it is used in the googletest, is corresponding to
the term _[Test Case](http://glossary.istqb.org/search/test%20case)_ of ISTQB
and others.
The term _Test_ is commonly of broad enough sense, including ISTQB's
definition of _Test Case_, so it's not much of a problem here. But the
term _Test Case_ as used in Google Test is of contradictory sense and thus confusing.
Unfortunately replacing the term _Test Case_ by _Test Suite_ throughout
the Google C++ Testing Framework is not easy without breaking dependent
projects, as `TestCase` is part of the public API at various places.
Unfortunately replacing the term _Test Case_ by _Test Suite_ throughout the
googletest is not easy without breaking dependent projects, as `TestCase` is
part of the public API at various places.
So for the time being, please be aware of the different definitions of
the terms:
Meaning | Google Test Term | [ISTQB](http://www.istqb.org/) Term
------- | ---------------- | -----------------------------------
Exercise a particular program path with specific input values and verify the results | [TEST()](#simple-tests) | [Test Case](http://glossary.istqb.org/search/test%20case)
A set of several tests related to one component | [Test Case](#basic-concepts) | [Test Suite](http://glossary.istqb.org/search/test%20suite)
Meaning | googletest Term | [ISTQB](http://www.istqb.org/) Term
:----------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------- | :----------------------------------
Exercise a particular program path with specific input values and verify the results | [TEST()](#simple-tests) | [Test Case](http://glossary.istqb.org/search/test%20case)
A set of several tests related to one component | [TestCase](https://g3doc.corp.google.com/third_party/googletest/googletest/g3doc/primer.md#basic-concepts) | [TestSuite](http://glossary.istqb.org/search/test%20suite)
# Setting up a New Test Project #
## Basic Concepts
To write a test program using Google Test, you need to compile Google
Test into a library and link your test with it. We provide build
files for some popular build systems: `msvc/` for Visual Studio,
`xcode/` for Mac Xcode, `make/` for GNU make, `codegear/` for Borland
C++ Builder, and the autotools script (deprecated) and
`CMakeLists.txt` for CMake (recommended) in the Google Test root
directory. If your build system is not on this list, you can take a
look at `make/Makefile` to learn how Google Test should be compiled
(basically you want to compile `src/gtest-all.cc` with `GTEST_ROOT`
and `GTEST_ROOT/include` in the header search path, where `GTEST_ROOT`
is the Google Test root directory).
When using googletest, you start by writing *assertions*, which are statements
that check whether a condition is true. An assertion's result can be *success*,
*nonfatal failure*, or *fatal failure*. If a fatal failure occurs, it aborts the
current function; otherwise the program continues normally.
Once you are able to compile the Google Test library, you should
create a project or build target for your test program. Make sure you
have `GTEST_ROOT/include` in the header search path so that the
compiler can find `"gtest/gtest.h"` when compiling your test. Set up
your test project to link with the Google Test library (for example,
in Visual Studio, this is done by adding a dependency on
`gtest.vcproj`).
*Tests* use assertions to verify the tested code's behavior. If a test crashes
or has a failed assertion, then it *fails*; otherwise it *succeeds*.
If you still have questions, take a look at how Google Test's own
tests are built and use them as examples.
# Basic Concepts #
When using Google Test, you start by writing _assertions_, which are statements
that check whether a condition is true. An assertion's result can be _success_,
_nonfatal failure_, or _fatal failure_. If a fatal failure occurs, it aborts
the current function; otherwise the program continues normally.
_Tests_ use assertions to verify the tested code's behavior. If a test crashes
or has a failed assertion, then it _fails_; otherwise it _succeeds_.
A _test case_ contains one or many tests. You should group your tests into test
A *test case* contains one or many tests. You should group your tests into test
cases that reflect the structure of the tested code. When multiple tests in a
test case need to share common objects and subroutines, you can put them into a
_test fixture_ class.
*test fixture* class.
A _test program_ can contain multiple test cases.
A *test program* can contain multiple test cases.
We'll now explain how to write a test program, starting at the individual
assertion level and building up to tests and test cases.
# Assertions #
## Assertions
Google Test assertions are macros that resemble function calls. You test a
class or function by making assertions about its behavior. When an assertion
fails, Google Test prints the assertion's source file and line number location,
along with a failure message. You may also supply a custom failure message
which will be appended to Google Test's message.
googletest assertions are macros that resemble function calls. You test a class
or function by making assertions about its behavior. When an assertion fails,
googletest prints the assertion's source file and line number location, along
with a failure message. You may also supply a custom failure message which will
be appended to googletest's message.
The assertions come in pairs that test the same thing but have different
effects on the current function. `ASSERT_*` versions generate fatal failures
when they fail, and **abort the current function**. `EXPECT_*` versions generate
nonfatal failures, which don't abort the current function. Usually `EXPECT_*`
are preferred, as they allow more than one failures to be reported in a test.
However, you should use `ASSERT_*` if it doesn't make sense to continue when
the assertion in question fails.
The assertions come in pairs that test the same thing but have different effects
on the current function. `ASSERT_*` versions generate fatal failures when they
fail, and **abort the current function**. `EXPECT_*` versions generate nonfatal
failures, which don't abort the current function. Usually `EXPECT_*` are
preferred, as they allow more than one failure to be reported in a test.
However, you should use `ASSERT_*` if it doesn't make sense to continue when the
assertion in question fails.
Since a failed `ASSERT_*` returns from the current function immediately,
possibly skipping clean-up code that comes after it, it may cause a space leak.
Depending on the nature of the leak, it may or may not be worth fixing - so
keep this in mind if you get a heap checker error in addition to assertion
errors.
Depending on the nature of the leak, it may or may not be worth fixing - so keep
this in mind if you get a heap checker error in addition to assertion errors.
To provide a custom failure message, simply stream it into the macro using the
`<<` operator, or a sequence of such operators. An example:
```
```c++
ASSERT_EQ(x.size(), y.size()) << "Vectors x and y are of unequal length";
for (int i = 0; i < x.size(); ++i) {
@ -139,50 +133,53 @@ macro--in particular, C strings and `string` objects. If a wide string
(`wchar_t*`, `TCHAR*` in `UNICODE` mode on Windows, or `std::wstring`) is
streamed to an assertion, it will be translated to UTF-8 when printed.
## Basic Assertions ##
### Basic Assertions
These assertions do basic true/false condition testing.
| **Fatal assertion** | **Nonfatal assertion** | **Verifies** |
|:--------------------|:-----------------------|:-------------|
| `ASSERT_TRUE(`_condition_`)`; | `EXPECT_TRUE(`_condition_`)`; | _condition_ is true |
| `ASSERT_FALSE(`_condition_`)`; | `EXPECT_FALSE(`_condition_`)`; | _condition_ is false |
Fatal assertion | Nonfatal assertion | Verifies
-------------------------- | -------------------------- | --------------------
`ASSERT_TRUE(condition);` | `EXPECT_TRUE(condition);` | `condition` is true
`ASSERT_FALSE(condition);` | `EXPECT_FALSE(condition);` | `condition` is false
Remember, when they fail, `ASSERT_*` yields a fatal failure and
returns from the current function, while `EXPECT_*` yields a nonfatal
failure, allowing the function to continue running. In either case, an
assertion failure means its containing test fails.
Remember, when they fail, `ASSERT_*` yields a fatal failure and returns from the
current function, while `EXPECT_*` yields a nonfatal failure, allowing the
function to continue running. In either case, an assertion failure means its
containing test fails.
_Availability_: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
## Binary Comparison ##
### Binary Comparison
This section describes assertions that compare two values.
| **Fatal assertion** | **Nonfatal assertion** | **Verifies** |
|:--------------------|:-----------------------|:-------------|
|`ASSERT_EQ(`_val1_`, `_val2_`);`|`EXPECT_EQ(`_val1_`, `_val2_`);`| _val1_ `==` _val2_ |
|`ASSERT_NE(`_val1_`, `_val2_`);`|`EXPECT_NE(`_val1_`, `_val2_`);`| _val1_ `!=` _val2_ |
|`ASSERT_LT(`_val1_`, `_val2_`);`|`EXPECT_LT(`_val1_`, `_val2_`);`| _val1_ `<` _val2_ |
|`ASSERT_LE(`_val1_`, `_val2_`);`|`EXPECT_LE(`_val1_`, `_val2_`);`| _val1_ `<=` _val2_ |
|`ASSERT_GT(`_val1_`, `_val2_`);`|`EXPECT_GT(`_val1_`, `_val2_`);`| _val1_ `>` _val2_ |
|`ASSERT_GE(`_val1_`, `_val2_`);`|`EXPECT_GE(`_val1_`, `_val2_`);`| _val1_ `>=` _val2_ |
Fatal assertion | Nonfatal assertion | Verifies
------------------------ | ------------------------ | --------------
`ASSERT_EQ(val1, val2);` | `EXPECT_EQ(val1, val2);` | `val1 == val2`
`ASSERT_NE(val1, val2);` | `EXPECT_NE(val1, val2);` | `val1 != val2`
`ASSERT_LT(val1, val2);` | `EXPECT_LT(val1, val2);` | `val1 < val2`
`ASSERT_LE(val1, val2);` | `EXPECT_LE(val1, val2);` | `val1 <= val2`
`ASSERT_GT(val1, val2);` | `EXPECT_GT(val1, val2);` | `val1 > val2`
`ASSERT_GE(val1, val2);` | `EXPECT_GE(val1, val2);` | `val1 >= val2`
In the event of a failure, Google Test prints both _val1_ and _val2_.
Value arguments must be comparable by the assertion's comparison
operator or you'll get a compiler error. We used to require the
arguments to support the `<<` operator for streaming to an `ostream`,
but it's no longer necessary since v1.6.0 (if `<<` is supported, it
will be called to print the arguments when the assertion fails;
otherwise Google Test will attempt to print them in the best way it
can. For more details and how to customize the printing of the
arguments, see this Google Mock [recipe](../../googlemock/docs/CookBook.md#teaching-google-mock-how-to-print-your-values).).
Value arguments must be comparable by the assertion's comparison operator or
you'll get a compiler error. We used to require the arguments to support the
`<<` operator for streaming to an `ostream`, but it's no longer necessary. If
`<<` is supported, it will be called to print the arguments when the assertion
fails; otherwise googletest will attempt to print them in the best way it can.
For more details and how to customize the printing of the arguments, see
gMock [recipe](../../googlemock/docs/CookBook.md#teaching-google-mock-how-to-print-your-values).).
These assertions can work with a user-defined type, but only if you define the
corresponding comparison operator (e.g. `==`, `<`, etc). If the corresponding
operator is defined, prefer using the `ASSERT_*()` macros because they will
print out not only the result of the comparison, but the two operands as well.
corresponding comparison operator (e.g. `==`, `<`, etc). Since this is
discouraged by the Google [C++ Style
Guide](https://google.github.io/styleguide/cppguide.html#Operator_Overloading),
you may need to use `ASSERT_TRUE()` or `EXPECT_TRUE()` to assert the equality of
two objects of a user-defined type.
However, when possible, `ASSERT_EQ(actual, expected)` is preferred to
`ASSERT_TRUE(actual == expected)`, since it tells you `actual` and `expected`'s
values on failure.
Arguments are always evaluated exactly once. Therefore, it's OK for the
arguments to have side effects. However, as with any ordinary C/C++ function,
@ -193,117 +190,153 @@ evaluation order.
`ASSERT_EQ()` does pointer equality on pointers. If used on two C strings, it
tests if they are in the same memory location, not if they have the same value.
Therefore, if you want to compare C strings (e.g. `const char*`) by value, use
`ASSERT_STREQ()` , which will be described later on. In particular, to assert
that a C string is `NULL`, use `ASSERT_STREQ(NULL, c_string)` . However, to
compare two `string` objects, you should use `ASSERT_EQ`.
`ASSERT_STREQ()`, which will be described later on. In particular, to assert
that a C string is `NULL`, use `ASSERT_STREQ(c_string, NULL)`. Consider use
`ASSERT_EQ(c_string, nullptr)` if c++11 is supported. To compare two `string`
objects, you should use `ASSERT_EQ`.
When doing pointer comparisons use `*_EQ(ptr, nullptr)` and `*_NE(ptr, nullptr)`
instead of `*_EQ(ptr, NULL)` and `*_NE(ptr, NULL)`. This is because `nullptr` is
typed while `NULL` is not. See [FAQ](faq#Why_does_googletest_support_EXPECT_EQ)
for more details.
If you're working with floating point numbers, you may want to use the floating
point variations of some of these macros in order to avoid problems caused by
rounding. See [Advanced googletest Topics](advanced) for details.
Macros in this section work with both narrow and wide string objects (`string`
and `wstring`).
_Availability_: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
_Historical note_: Before February 2016 `*_EQ` had a convention of calling it as
`ASSERT_EQ(expected, actual)`, so lots of existing code uses this order.
Now `*_EQ` treats both parameters in the same way.
**Historical note**: Before February 2016 `*_EQ` had a convention of calling it
as `ASSERT_EQ(expected, actual)`, so lots of existing code uses this order. Now
`*_EQ` treats both parameters in the same way.
## String Comparison ##
### String Comparison
The assertions in this group compare two **C strings**. If you want to compare
two `string` objects, use `EXPECT_EQ`, `EXPECT_NE`, and etc instead.
| **Fatal assertion** | **Nonfatal assertion** | **Verifies** |
|:--------------------|:-----------------------|:-------------|
| `ASSERT_STREQ(`_str1_`, `_str2_`);` | `EXPECT_STREQ(`_str1_`, `_str2_`);` | the two C strings have the same content |
| `ASSERT_STRNE(`_str1_`, `_str2_`);` | `EXPECT_STRNE(`_str1_`, `_str2_`);` | the two C strings have different content |
| `ASSERT_STRCASEEQ(`_str1_`, `_str2_`);`| `EXPECT_STRCASEEQ(`_str1_`, `_str2_`);` | the two C strings have the same content, ignoring case |
| `ASSERT_STRCASENE(`_str1_`, `_str2_`);`| `EXPECT_STRCASENE(`_str1_`, `_str2_`);` | the two C strings have different content, ignoring case |
| Fatal assertion | Nonfatal assertion | Verifies |
| ----------------------- | ----------------------- | ---------------------- |
| `ASSERT_STREQ(str1, | `EXPECT_STREQ(str1, | the two C strings have |
: str2);` : str2);` : the same content :
| `ASSERT_STRNE(str1, | `EXPECT_STRNE(str1, | the two C strings have |
: str2);` : str2);` : different contents :
| `ASSERT_STRCASEEQ(str1, | `EXPECT_STRCASEEQ(str1, | the two C strings have |
: str2);` : str2);` : the same content, :
: : : ignoring case :
| `ASSERT_STRCASENE(str1, | `EXPECT_STRCASENE(str1, | the two C strings have |
: str2);` : str2);` : different contents, :
: : : ignoring case :
Note that "CASE" in an assertion name means that case is ignored.
Note that "CASE" in an assertion name means that case is ignored. A `NULL`
pointer and an empty string are considered *different*.
`*STREQ*` and `*STRNE*` also accept wide C strings (`wchar_t*`). If a
comparison of two wide strings fails, their values will be printed as UTF-8
narrow strings.
`*STREQ*` and `*STRNE*` also accept wide C strings (`wchar_t*`). If a comparison
of two wide strings fails, their values will be printed as UTF-8 narrow strings.
A `NULL` pointer and an empty string are considered _different_.
**Availability**: Linux, Windows, Mac.
_Availability_: Linux, Windows, Mac.
**See also**: For more string comparison tricks (substring, prefix, suffix, and
regular expression matching, for example), see
[this](https://github.com/google/googletest/blob/master/googletest/docs/advanced.md)
in the Advanced googletest Guide.
See also: For more string comparison tricks (substring, prefix, suffix, and
regular expression matching, for example), see the [Advanced Google Test Guide](advanced.md).
# Simple Tests #
## Simple Tests
To create a test:
1. Use the `TEST()` macro to define and name a test function, These are ordinary C++ functions that don't return a value.
1. In this function, along with any valid C++ statements you want to include, use the various Google Test assertions to check values.
1. The test's result is determined by the assertions; if any assertion in the test fails (either fatally or non-fatally), or if the test crashes, the entire test fails. Otherwise, it succeeds.
```
TEST(testCaseName, testName) {
... test body ...
1. Use the `TEST()` macro to define and name a test function, These are
ordinary C++ functions that don't return a value.
1. In this function, along with any valid C++ statements you want to include,
use the various googletest assertions to check values.
1. The test's result is determined by the assertions; if any assertion in the
test fails (either fatally or non-fatally), or if the test crashes, the
entire test fails. Otherwise, it succeeds.
```c++
TEST(TestCaseName, TestName) {
... test body ...
}
```
`TEST()` arguments go from general to specific. The _first_ argument is the
name of the test case, and the _second_ argument is the test's name within the
test case. Both names must be valid C++ identifiers, and they should not contain underscore (`_`). A test's _full name_ consists of its containing test case and its
individual name. Tests from different test cases can have the same individual
name.
`TEST()` arguments go from general to specific. The *first* argument is the name
of the test case, and the *second* argument is the test's name within the test
case. Both names must be valid C++ identifiers, and they should not contain
underscore (`_`). A test's *full name* consists of its containing test case and
its individual name. Tests from different test cases can have the same
individual name.
For example, let's take a simple integer function:
```
int Factorial(int n); // Returns the factorial of n
```c++
int Factorial(int n); // Returns the factorial of n
```
A test case for this function might look like:
```
```c++
// Tests factorial of 0.
TEST(FactorialTest, HandlesZeroInput) {
EXPECT_EQ(1, Factorial(0));
EXPECT_EQ(Factorial(0), 1);
}
// Tests factorial of positive numbers.
TEST(FactorialTest, HandlesPositiveInput) {
EXPECT_EQ(1, Factorial(1));
EXPECT_EQ(2, Factorial(2));
EXPECT_EQ(6, Factorial(3));
EXPECT_EQ(40320, Factorial(8));
EXPECT_EQ(Factorial(1), 1);
EXPECT_EQ(Factorial(2), 2);
EXPECT_EQ(Factorial(3), 6);
EXPECT_EQ(Factorial(8), 40320);
}
```
Google Test groups the test results by test cases, so logically-related tests
googletest groups the test results by test cases, so logically-related tests
should be in the same test case; in other words, the first argument to their
`TEST()` should be the same. In the above example, we have two tests,
`HandlesZeroInput` and `HandlesPositiveInput`, that belong to the same test
case `FactorialTest`.
`HandlesZeroInput` and `HandlesPositiveInput`, that belong to the same test case
`FactorialTest`.
_Availability_: Linux, Windows, Mac.
When naming your test cases and tests, you should follow the same convention as
for [naming functions and
classes](https://google.github.io/styleguide/cppguide.html#Function_Names).
# Test Fixtures: Using the Same Data Configuration for Multiple Tests #
**Availability**: Linux, Windows, Mac.
If you find yourself writing two or more tests that operate on similar data,
you can use a _test fixture_. It allows you to reuse the same configuration of
## Test Fixtures: Using the Same Data Configuration for Multiple Tests
If you find yourself writing two or more tests that operate on similar data, you
can use a *test fixture*. It allows you to reuse the same configuration of
objects for several different tests.
To create a fixture, just:
1. Derive a class from `::testing::Test` . Start its body with `protected:` or `public:` as we'll want to access fixture members from sub-classes.
1. Inside the class, declare any objects you plan to use.
1. If necessary, write a default constructor or `SetUp()` function to prepare the objects for each test. A common mistake is to spell `SetUp()` as `Setup()` with a small `u` - don't let that happen to you.
1. If necessary, write a destructor or `TearDown()` function to release any resources you allocated in `SetUp()` . To learn when you should use the constructor/destructor and when you should use `SetUp()/TearDown()`, read this [FAQ entry](faq.md#should-i-use-the-constructordestructor-of-the-test-fixture-or-the-set-uptear-down-function).
1. If needed, define subroutines for your tests to share.
To create a fixture:
1. Derive a class from `::testing::Test` . Start its body with `protected:` as
we'll want to access fixture members from sub-classes.
1. Inside the class, declare any objects you plan to use.
1. If necessary, write a default constructor or `SetUp()` function to prepare
the objects for each test. A common mistake is to spell `SetUp()` as
**`Setup()`** with a small `u` - Use `override` in C++11 to make sure you
spelled it correctly
1. If necessary, write a destructor or `TearDown()` function to release any
resources you allocated in `SetUp()` . To learn when you should use the
constructor/destructor and when you should use `SetUp()/TearDown()`, read
this [FAQ](faq#CtorVsSetUp) entry.
1. If needed, define subroutines for your tests to share.
When using a fixture, use `TEST_F()` instead of `TEST()` as it allows you to
access objects and subroutines in the test fixture:
```
TEST_F(test_case_name, test_name) {
... test body ...
```c++
TEST_F(TestCaseName, TestName) {
... test body ...
}
```
Like `TEST()`, the first argument is the test case name, but for `TEST_F()`
this must be the name of the test fixture class. You've probably guessed: `_F`
is for fixture.
Like `TEST()`, the first argument is the test case name, but for `TEST_F()` this
must be the name of the test fixture class. You've probably guessed: `_F` is for
fixture.
Unfortunately, the C++ macro system does not allow us to create a single macro
that can handle both types of tests. Using the wrong macro causes a compiler
@ -313,22 +346,24 @@ Also, you must first define a test fixture class before using it in a
`TEST_F()`, or you'll get the compiler error "`virtual outside class
declaration`".
For each test defined with `TEST_F()`, Google Test will:
1. Create a _fresh_ test fixture at runtime
1. Immediately initialize it via `SetUp()`
1. Run the test
1. Clean up by calling `TearDown()`
1. Delete the test fixture. Note that different tests in the same test case have different test fixture objects, and Google Test always deletes a test fixture before it creates the next one. Google Test does not reuse the same test fixture for multiple tests. Any changes one test makes to the fixture do not affect other tests.
For each test defined with `TEST_F()` , googletest will create a *fresh* test
fixture at runtime, immediately initialize it via `SetUp()` , run the test,
clean up by calling `TearDown()` , and then delete the test fixture. Note that
different tests in the same test case have different test fixture objects, and
googletest always deletes a test fixture before it creates the next one.
googletest does **not** reuse the same test fixture for multiple tests. Any
changes one test makes to the fixture do not affect other tests.
As an example, let's write tests for a FIFO queue class named `Queue`, which
has the following interface:
```
template <typename E> // E is the element type.
As an example, let's write tests for a FIFO queue class named `Queue`, which has
the following interface:
```c++
template <typename E> // E is the element type.
class Queue {
public:
Queue();
void Enqueue(const E& element);
E* Dequeue(); // Returns NULL if the queue is empty.
E* Dequeue(); // Returns NULL if the queue is empty.
size_t size() const;
...
};
@ -336,16 +371,17 @@ class Queue {
First, define a fixture class. By convention, you should give it the name
`FooTest` where `Foo` is the class being tested.
```
```c++
class QueueTest : public ::testing::Test {
protected:
virtual void SetUp() {
q1_.Enqueue(1);
q2_.Enqueue(2);
q2_.Enqueue(3);
void SetUp() override {
q1_.Enqueue(1);
q2_.Enqueue(2);
q2_.Enqueue(3);
}
// virtual void TearDown() {}
// void TearDown() override {}
Queue<int> q0_;
Queue<int> q1_;
@ -357,85 +393,101 @@ In this case, `TearDown()` is not needed since we don't have to clean up after
each test, other than what's already done by the destructor.
Now we'll write tests using `TEST_F()` and this fixture.
```
```c++
TEST_F(QueueTest, IsEmptyInitially) {
EXPECT_EQ(0, q0_.size());
EXPECT_EQ(q0_.size(), 0);
}
TEST_F(QueueTest, DequeueWorks) {
int* n = q0_.Dequeue();
EXPECT_EQ(NULL, n);
EXPECT_EQ(n, nullptr);
n = q1_.Dequeue();
ASSERT_TRUE(n != NULL);
EXPECT_EQ(1, *n);
EXPECT_EQ(0, q1_.size());
ASSERT_NE(n, nullptr);
EXPECT_EQ(*n, 1);
EXPECT_EQ(q1_.size(), 0);
delete n;
n = q2_.Dequeue();
ASSERT_TRUE(n != NULL);
EXPECT_EQ(2, *n);
EXPECT_EQ(1, q2_.size());
ASSERT_NE(n, nullptr);
EXPECT_EQ(*n, 2);
EXPECT_EQ(q2_.size(), 1);
delete n;
}
```
The above uses both `ASSERT_*` and `EXPECT_*` assertions. The rule of thumb is
to use `EXPECT_*` when you want the test to continue to reveal more errors
after the assertion failure, and use `ASSERT_*` when continuing after failure
doesn't make sense. For example, the second assertion in the `Dequeue` test is
`ASSERT_TRUE(n != NULL)`, as we need to dereference the pointer `n` later,
which would lead to a segfault when `n` is `NULL`.
to use `EXPECT_*` when you want the test to continue to reveal more errors after
the assertion failure, and use `ASSERT_*` when continuing after failure doesn't
make sense. For example, the second assertion in the `Dequeue` test is
=ASSERT_NE(nullptr, n)=, as we need to dereference the pointer `n` later, which
would lead to a segfault when `n` is `NULL`.
When these tests run, the following happens:
1. Google Test constructs a `QueueTest` object (let's call it `t1` ).
1. `t1.SetUp()` initializes `t1` .
1. The first test ( `IsEmptyInitially` ) runs on `t1` .
1. `t1.TearDown()` cleans up after the test finishes.
1. `t1` is destructed.
1. The above steps are repeated on another `QueueTest` object, this time running the `DequeueWorks` test.
_Availability_: Linux, Windows, Mac.
1. googletest constructs a `QueueTest` object (let's call it `t1` ).
1. `t1.SetUp()` initializes `t1` .
1. The first test ( `IsEmptyInitially` ) runs on `t1` .
1. `t1.TearDown()` cleans up after the test finishes.
1. `t1` is destructed.
1. The above steps are repeated on another `QueueTest` object, this time
running the `DequeueWorks` test.
_Note_: Google Test automatically saves all _Google Test_ flags when a test
object is constructed, and restores them when it is destructed.
**Availability**: Linux, Windows, Mac.
# Invoking the Tests #
## Invoking the Tests
`TEST()` and `TEST_F()` implicitly register their tests with Google Test. So, unlike with many other C++ testing frameworks, you don't have to re-list all your defined tests in order to run them.
`TEST()` and `TEST_F()` implicitly register their tests with googletest. So,
unlike with many other C++ testing frameworks, you don't have to re-list all
your defined tests in order to run them.
After defining your tests, you can run them with `RUN_ALL_TESTS()` , which returns `0` if all the tests are successful, or `1` otherwise. Note that `RUN_ALL_TESTS()` runs _all tests_ in your link unit -- they can be from different test cases, or even different source files.
After defining your tests, you can run them with `RUN_ALL_TESTS()` , which
returns `0` if all the tests are successful, or `1` otherwise. Note that
`RUN_ALL_TESTS()` runs *all tests* in your link unit -- they can be from
different test cases, or even different source files.
When invoked, the `RUN_ALL_TESTS()` macro:
1. Saves the state of all Google Test flags.
1. Creates a test fixture object for the first test.
1. Initializes it via `SetUp()`.
1. Runs the test on the fixture object.
1. Cleans up the fixture via `TearDown()`.
1. Deletes the fixture.
1. Restores the state of all Google Test flags.
1. Repeats the above steps for the next test, until all tests have run.
In addition, if the test fixture's constructor generates a fatal failure in
step 2, there is no point for step 3 - 5 and they are thus skipped. Similarly,
if step 3 generates a fatal failure, step 4 will be skipped.
1. Saves the state of all googletest flags
_Important_: You must not ignore the return value of `RUN_ALL_TESTS()`, or `gcc`
will give you a compiler error. The rationale for this design is that the
automated testing service determines whether a test has passed based on its
exit code, not on its stdout/stderr output; thus your `main()` function must
return the value of `RUN_ALL_TESTS()`.
* Creates a test fixture object for the first test.
Also, you should call `RUN_ALL_TESTS()` only **once**. Calling it more than once
conflicts with some advanced Google Test features (e.g. thread-safe death
tests) and thus is not supported.
* Initializes it via `SetUp()`.
_Availability_: Linux, Windows, Mac.
* Runs the test on the fixture object.
# Writing the main() Function #
* Cleans up the fixture via `TearDown()`.
* Deletes the fixture.
1. Restores the state of all googletest flags
* Repeats the above steps for the next test, until all tests have run.
If a fatal failure happens the subsequent steps will be skipped.
> IMPORTANT: You must **not** ignore the return value of `RUN_ALL_TESTS()`, or
> you will get a compiler error. The rationale for this design is that the
> automated testing service determines whether a test has passed based on its
> exit code, not on its stdout/stderr output; thus your `main()` function must
> return the value of `RUN_ALL_TESTS()`.
>
> Also, you should call `RUN_ALL_TESTS()` only **once**. Calling it more than
> once conflicts with some advanced googletest features (e.g. thread-safe [death
> tests](advanced#death-tests)) and thus is not supported.
**Availability**: Linux, Windows, Mac.
## Writing the main() Function
In `google3`, the simplest approach is to use the default main() function
provided by linking in `"//testing/base/public:gtest_main"`. If that doesn't
cover what you need, you should write your own main() function, which should
return the value of `RUN_ALL_TESTS()`. Link to `"//testing/base/public:gunit"`.
You can start from this boilerplate:
```
```c++
#include "this/package/foo.h"
#include "gtest/gtest.h"
@ -448,24 +500,24 @@ class FooTest : public ::testing::Test {
// is empty.
FooTest() {
// You can do set-up work for each test here.
// You can do set-up work for each test here.
}
virtual ~FooTest() {
// You can do clean-up work that doesn't throw exceptions here.
~FooTest() override {
// You can do clean-up work that doesn't throw exceptions here.
}
// If the constructor and destructor are not enough for setting up
// and cleaning up each test, you can define the following methods:
virtual void SetUp() {
// Code here will be called immediately after the constructor (right
// before each test).
void SetUp() override {
// Code here will be called immediately after the constructor (right
// before each test).
}
virtual void TearDown() {
// Code here will be called immediately after each test (right
// before the destructor).
void TearDown() override {
// Code here will be called immediately after each test (right
// before the destructor).
}
// Objects declared here can be used by all tests in the test case for Foo.
@ -473,10 +525,10 @@ class FooTest : public ::testing::Test {
// Tests that the Foo::Bar() method does Abc.
TEST_F(FooTest, MethodBarDoesAbc) {
const string input_filepath = "this/package/testdata/myinputfile.dat";
const string output_filepath = "this/package/testdata/myoutputfile.dat";
const std::string input_filepath = "this/package/testdata/myinputfile.dat";
const std::string output_filepath = "this/package/testdata/myoutputfile.dat";
Foo f;
EXPECT_EQ(0, f.Bar(input_filepath, output_filepath));
EXPECT_EQ(f.Bar(input_filepath, output_filepath), 0);
}
// Tests that Foo does Xyz.
@ -492,45 +544,45 @@ int main(int argc, char **argv) {
}
```
The `::testing::InitGoogleTest()` function parses the command line for Google
Test 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 [AdvancedGuide](advanced.md).
You must call this function before calling `RUN_ALL_TESTS()`, or the flags
won't be properly initialized.
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
[AdvancedGuide](advanced.md). You **must** call this function before calling
`RUN_ALL_TESTS()`, or the flags won't be properly initialized.
On Windows, `InitGoogleTest()` also works with wide strings, so it can be used
in programs compiled in `UNICODE` mode as well.
But maybe you think that writing all those main() functions is too much work? We agree with you completely and that's why Google Test provides a basic implementation of main(). If it fits your needs, then just link your test with gtest\_main library and you are good to go.
But maybe you think that writing all those main() functions is too much work? We
agree with you completely and that's why Google Test provides a basic
implementation of main(). If it fits your needs, then just link your test with
gtest\_main library and you are good to go.
## Important note for Visual C++ users ##
If you put your tests into a library and your `main()` function is in a different library or in your .exe file, those tests will not run. The reason is a [bug](https://connect.microsoft.com/feedback/viewfeedback.aspx?FeedbackID=244410&siteid=210) in Visual C++. When you define your tests, Google Test creates certain static objects to register them. These objects are not referenced from elsewhere but their constructors are still supposed to run. When Visual C++ linker sees that nothing in the library is referenced from other places it throws the library out. You have to reference your library with tests from your main program to keep the linker from discarding it. Here is how to do it. Somewhere in your library code declare a function:
```
__declspec(dllexport) int PullInMyLibrary() { return 0; }
```
If you put your tests in a static library (not DLL) then `__declspec(dllexport)` is not required. Now, in your main program, write a code that invokes that function:
```
int PullInMyLibrary();
static int dummy = PullInMyLibrary();
```
This will keep your tests referenced and will make them register themselves at startup.
NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`.
In addition, if you define your tests in a static library, add `/OPT:NOREF` to your main program linker options. If you use MSVC++ IDE, go to your .exe project properties/Configuration Properties/Linker/Optimization and set References setting to `Keep Unreferenced Data (/OPT:NOREF)`. This will keep Visual C++ linker from discarding individual symbols generated by your tests from the final executable.
## Creating and Building Test Programs
There is one more pitfall, though. If you use Google Test as a static library (that's how it is defined in gtest.vcproj) your tests must also reside in a static library. If you have to have them in a DLL, you _must_ change Google Test to build into a DLL as well. Otherwise your tests will not run correctly or will not run at all. The general conclusion here is: make your life easier - do not write your tests in libraries!
Now that we've learned how to write a test program, we need to tell the build
system to build it. The exact steps differ from one OS to another.
# Where to Go from Here #
If you work on Linux, follow the instructions [here](howto_cpp#LinuxTarget).
Congratulations! You've learned the Google Test basics. You can start writing
and running Google Test tests, read some [samples](samples.md), or continue with
[AdvancedGuide](advanced.md), which describes many more useful Google Test features.
If you work on the Mac, follow the instructions [here](howto_cpp_mac).
# Known Limitations #
If you work on Windows, consult existing test programs in your project, as the
syntax for a test program build target may differ slightly from project to
project. When compiling googletest and your tests, please do **not** use the
`/Wp64` MSVC flag. It is broken and
[deprecated](http://msdn.microsoft.com/en-us/library/yt4xw8fh.aspx) by
Microsoft. We don't guarantee that googletest will compile warning-free with
that flag (as it's often technically infeasible given the flag's broken nature).
Google Test is designed to be thread-safe. The implementation is
thread-safe on systems where the `pthreads` library is available. It
is currently _unsafe_ to use Google Test assertions from two threads
concurrently on other systems (e.g. Windows). In most tests this is
not an issue as usually the assertions are done in the main thread. If
you want to help, you can volunteer to implement the necessary
synchronization primitives in `gtest-port.h` for your platform.
## Known Limitations
* Google Test is designed to be thread-safe. The implementation is thread-safe
on systems where the `pthreads` library is available. It is currently
_unsafe_ to use Google Test assertions from two threads concurrently on
other systems (e.g. Windows). In most tests this is not an issue as usually
the assertions are done in the main thread. If you want to help, you can
volunteer to implement the necessary synchronization primitives in
`gtest-port.h` for your platform.

34
googletest/docs/samples.md
View File

@ -1,14 +1,22 @@
If you're like us, you'd like to look at some Google Test sample code. The
[samples folder](../samples) has a number of well-commented samples showing how to use a
variety of Google Test features.
# Googletest Samples {#samples}
* [Sample #1](../samples/sample1_unittest.cc) shows the basic steps of using Google Test to test C++ functions.
* [Sample #2](../samples/sample2_unittest.cc) shows a more complex unit test for a class with multiple member functions.
* [Sample #3](../samples/sample3_unittest.cc) uses a test fixture.
* [Sample #4](../samples/sample4_unittest.cc) is another basic example of using Google Test.
* [Sample #5](../samples/sample5_unittest.cc) teaches how to reuse a test fixture in multiple test cases by deriving sub-fixtures from it.
* [Sample #6](../samples/sample6_unittest.cc) demonstrates type-parameterized tests.
* [Sample #7](../samples/sample7_unittest.cc) teaches the basics of value-parameterized tests.
* [Sample #8](../samples/sample8_unittest.cc) shows using `Combine()` in value-parameterized tests.
* [Sample #9](../samples/sample9_unittest.cc) shows use of the listener API to modify Google Test's console output and the use of its reflection API to inspect test results.
* [Sample #10](../samples/sample10_unittest.cc) shows use of the listener API to implement a primitive memory leak checker.
If you're like us, you'd like to look at [googletest
samples.](https://github.com/google/googletest/tree/master/googletest/samples)
The sample directory has a number of well-commented samples showing how to use a
variety of googletest features.
* Sample #1 shows the basic steps of using googletest to test C++ functions.
* Sample #2 shows a more complex unit test for a class with multiple member
functions.
* Sample #3 uses a test fixture.
* Sample #4 teaches you how to use googletest and `googletest.h` together to
get the best of both libraries.
* Sample #5 puts shared testing logic in a base test fixture, and reuses it in
derived fixtures.
* Sample #6 demonstrates type-parameterized tests.
* Sample #7 teaches the basics of value-parameterized tests.
* Sample #8 shows using `Combine()` in value-parameterized tests.
* Sample #9 shows use of the listener API to modify Google Test's console
output and the use of its reflection API to inspect test results.
* Sample #10 shows use of the listener API to implement a primitive memory
leak checker.