Add CPM_SOURCE_CACHE environmental variable support and keep existing sources (#83)

* read CPM_SOURCE_CACHE from environment

* update readme

* cleanup

* add cache tests

.gitignore

@@ -1,12 +1,3 @@
-CMakeCache.txt
-CMakeFiles
-CMakeScripts
-Testing
-Makefile
-cmake_install.cmake
-install_manifest.txt
-compile_commands.json
-CTestTestfile.cmake
-build
-.vscode
-.DS_Store
+/build*
+/.vscode
+*.DS_Store

.travis.yml

@@ -1,4 +1,3 @@
-
 language: cpp
 sudo: require
 dist: xenial
@@ -25,11 +24,11 @@ matrix:
     - os: linux
       compiler: clang
       addons:
-          apt:
-              sources: *all_sources
-              packages:
-                - g++-8
-                - clang-6.0
+        apt:
+          sources: *all_sources
+          packages:
+            - g++-8
+            - clang-6.0
       env:
         - MATRIX_EVAL="export CC=clang-6.0; export CXX=clang++-6.0;"
 
@@ -48,5 +47,4 @@ script:
   - cmake -Htest -Bbuild/test
   - CTEST_OUTPUT_ON_FAILURE=1 cmake --build build/test --target test
   # examples
-  - python3 examples/run_all.py
- 
+  - python3 examples/build_all.py

README.md

@@ -50,24 +50,22 @@ cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 project(MyProject)
 
 # add executable
-add_executable(myProject myProject.cpp)
-set_target_properties(myProject PROPERTIES CXX_STANDARD 17)
+add_executable(tests tests.cpp)
 
 # add dependencies
 include(cmake/CPM.cmake)
 
 CPMAddPackage(
-  NAME LarsParser
-  VERSION 1.8
-  GIT_REPOSITORY https://github.com/TheLartians/Parser.git
-  OPTIONS
-    "LARS_PARSER_BUILD_GLUE_EXTENSION ON"
+  NAME Catch2
+  GITHUB_REPOSITORY catchorg/Catch2
+  VERSION 2.5.0
 )
 
-target_link_libraries(myProject LarsParser)
+# link dependencies
+target_link_libraries(tests Catch2)
 ```
 
-See the [examples directory](https://github.com/TheLartians/CPM/tree/master/examples) for more examples with source code.
+See the [examples directory](https://github.com/TheLartians/CPM/tree/master/examples) for more many examples with source code or the [wiki](https://github.com/TheLartians/CPM/wiki/More-Snippets) for many example snippets.
 
 ## Adding CPM
 
@@ -78,36 +76,38 @@ mkdir -p cmake
 wget -O cmake/CPM.cmake https://raw.githubusercontent.com/TheLartians/CPM/master/cmake/CPM.cmake
 ```
 
-You can also use CMake to download CPM for you. See the [wiki](https://github.com/TheLartians/CPM/wiki/Adding-CPM) for more details.
+You can even use CMake to download CPM for you. See the [wiki](https://github.com/TheLartians/CPM/wiki/Adding-CPM) for more details.
 
 ## Updating CPM
 
-To update CPM to the newest version, simply update the script in the project's cmake directory, for example by running the command above. Dependencies using CPM will automatically use the updated script of the outermost project.
+To update CPM to the newest version, update the script in the project's root directory, for example by running the command above. Dependencies using CPM will automatically use the updated script of the outermost project.
 
 ## Advantages
 
 - **Small and reusable projects** CPM takes care of all project dependencies, allowing developers to focus on creating small, well-tested frameworks.
-- **Cross-Platform** CPM adds projects via `add_subdirectory`, which is compatible with all cmake toolchains and generators.
+- **Cross-Platform** CPM adds projects via `add_subdirectory`, which is compatible with all CMake toolchains and generators.
 - **Reproducable builds** By using versioning via git tags it is ensured that a project will always be in the same state everywhere.
 - **Recursive dependencies** Ensures that no dependency is added twice and is added in the minimum required version.
 - **Plug-and-play** No need to install anything. Just add the script to your project and you're good to go.
 - **No packaging required** There is a good chance your existing projects already work as CPM dependencies.
-- **Simple source distribution** CPM makes including projects with source files and dependencies easy, reducing the need for monolithic header files.
+- **Simple source distribution** CPM makes including projects with source files and dependencies easy, reducing the need for monolithic header files or git submodules.
 
 ## Limitations
 
-- **No pre-built binaries** For every new project, all dependencies must be downloaded and built from scratch. A possible workaround is to use CPM to fetch a pre-built binary or to enable local packages (see [below](#local-packages)).
+- **No pre-built binaries** For every new build directory, all dependencies are initially downloaded and built from scratch. To avoid extra downloads it is recommend to set the [`CPM_SOURCE_CACHE`](#CPM_SOURCE_CACHE) environmental variable. Using a caching compiler such as [sccahe](https://github.com/mozilla/sccache) can drastically reduce build time.
 - **Dependent on good CMakeLists** Many libraries do not have CMakeLists that work well for subprojects. Luckily this is slowly changing, however, until then, some manual configuration may be required (see the snippets [below](#snippets)). For best practices on preparing your projects for CPM, see the [wiki](https://github.com/TheLartians/CPM/wiki/Preparing-projects-for-CPM). 
 - **First version used** In diamond-shaped dependency graphs (e.g. `A` depends on `C`@1.1 and `B`, which itself depends on `C`@1.2 the first added dependency will be used (in this case `C`@1.1). In this case, B requires a newer version of `C` than `A`, so CPM will emit an error. This can be resolved by updating the outermost dependency version.
 
 For projects with more complex needs and where an extra setup step doesn't matter, it is worth to check out fully featured C++ package managers such as [conan](https://conan.io), [vcpkg](https://github.com/microsoft/vcpkg) or [hunter](https://github.com/ruslo/hunter).
-Support for package managers is also [planned](https://github.com/TheLartians/CPM/issues/51) for a future version of CPM.
+Support for these package managers is also [planned](https://github.com/TheLartians/CPM/issues/51) for a future version of CPM.
 
 ## Options
 
-### CPM_SOURCE_ROOT
+### CPM_SOURCE_CACHE
 
-To avoid re-downloading dependencies, configure the project with the cmake option `-DCPM_SOURCE_ROOT=<path to an external download directory>`.
+To avoid re-downloading dependencies, CPM has an option `CPM_SOURCE_CACHE` that can be passed to CMake as `-DCPM_SOURCE_CACHE=<path to an external download directory>`.
+It can also be defined system-wide as an environmental variable, by adding `export CPM_SOURCE_CACHE=$HOME/.cache/CPM` to your `.bashrc` or `.bash_profile`.
+Note that passing the variable as a configure option to CMake will always override the value set by the environmental variable.
 
 ### CPM_USE_LOCAL_PACKAGES
 
@@ -158,7 +158,7 @@ CPMAddPackage(
 CPMAddPackage(
   NAME yaml-cpp
   GITHUB_REPOSITORY jbeder/yaml-cpp
-  # 0.6.2 uses depricated CMake syntax
+  # 0.6.2 uses deprecated CMake syntax
   VERSION 0.6.3
   # 0.6.3 is not released yet, so use a recent commit
   GIT_TAG 012269756149ae99745b6dafefd415843d7420bb 
@@ -247,4 +247,4 @@ For a full example on using CPM to download and configure lua with sol2 see [her
 
 ### Full Examples
 
-See the [examples directory](https://github.com/TheLartians/CPM/tree/master/examples) for full examples with source code.
+See the [examples directory](https://github.com/TheLartians/CPM/tree/master/examples) for full examples with source code and check out the [wiki](https://github.com/TheLartians/CPM/wiki/More-Snippets) for many more example snippets.

cmake/CPM.cmake

@@ -28,7 +28,7 @@
 
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
-set(CURRENT_CPM_VERSION 0.13) 
+set(CURRENT_CPM_VERSION 0.14) 
 
 if(CPM_DIRECTORY)
   if(NOT ${CPM_DIRECTORY} MATCHES ${CMAKE_CURRENT_LIST_DIR})
@@ -46,7 +46,14 @@ set(CPM_DRY_RUN OFF CACHE INTERNAL "Don't download or configure dependencies (fo
 
 option(CPM_USE_LOCAL_PACKAGES "Use locally installed packages (find_package)" OFF)
 option(CPM_LOCAL_PACKAGES_ONLY "Use only locally installed packages" OFF)
-set(CPM_SOURCE_ROOT OFF CACHE PATH "Directory to downlaod CPM dependencies")
+
+if(DEFINED ENV{CPM_SOURCE_CACHE})
+  set(CPM_SOURCE_CACHE_DEFAULT $ENV{CPM_SOURCE_CACHE})
+else()
+  set(CPM_SOURCE_CACHE_DEFAULT OFF)
+endif()
+
+set(CPM_SOURCE_CACHE ${CPM_SOURCE_CACHE_DEFAULT} CACHE PATH "Directory to downlaod CPM dependencies")
 
 include(FetchContent)
 include(CMakeParseArguments)
@@ -67,6 +74,7 @@ function(CPMAddPackage)
     GITHUB_REPOSITORY
     GITLAB_REPOSITORY
     SOURCE_DIR
+    DOWNLOAD_COMMAND
   )
 
   set(multiValueArgs
@@ -105,14 +113,6 @@ function(CPMAddPackage)
     set(CPM_ARGS_GIT_TAG v${CPM_ARGS_VERSION})
   endif()
 
-  set(FETCH_CONTENT_DECLARE_EXTRA_OPTS "")
-
-  if (CPM_SOURCE_ROOT AND NOT DEFINED CPM_ARGS_SOURCE_DIR)
-    string(TOLOWER ${CPM_ARGS_NAME} lname)
-    string(REPLACE "-" "_" source_path_name ${lname})
-    list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS SOURCE_DIR ${CPM_SOURCE_ROOT}/${source_path_name})
-  endif()
-
   list(APPEND CPM_ARGS_UNPARSED_ARGUMENTS GIT_TAG ${CPM_ARGS_GIT_TAG})
 
   if(CPM_ARGS_DOWNLOAD_ONLY)
@@ -159,7 +159,36 @@ function(CPMAddPackage)
     endforeach()
   endif()
 
-  CPM_DECLARE_PACKAGE(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION} ${CPM_ARGS_GIT_TAG} "${CPM_ARGS_UNPARSED_ARGUMENTS}" ${FETCH_CONTENT_DECLARE_EXTRA_OPTS})
+  set(FETCH_CONTENT_DECLARE_EXTRA_OPTS "")
+
+  if (DEFINED CPM_ARGS_GIT_TAG)
+    set(PACKAGE_INFO "${CPM_ARGS_GIT_TAG}")
+  else()
+    set(PACKAGE_INFO "${CPM_ARGS_VERSION}")
+  endif()
+
+  if (DEFINED CPM_ARGS_DOWNLOAD_COMMAND)
+    set(FETCH_CONTENT_DECLARE_EXTRA_OPTS DOWNLOAD_COMMAND ${CPM_ARGS_DOWNLOAD_COMMAND})
+  else()
+    if (CPM_SOURCE_CACHE AND NOT DEFINED CPM_ARGS_SOURCE_DIR)
+      string(TOLOWER ${CPM_ARGS_NAME} lower_case_name)
+      set(origin_parameters ${CPM_ARGS_UNPARSED_ARGUMENTS})
+      list(SORT origin_parameters)
+      string(SHA1 origin_hash "${origin_parameters}")
+      set(download_directory ${CPM_SOURCE_CACHE}/${lower_case_name}/${origin_hash})
+      list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS SOURCE_DIR ${download_directory})
+      if (EXISTS ${download_directory})
+        list(APPEND FETCH_CONTENT_DECLARE_EXTRA_OPTS DOWNLOAD_COMMAND ":")
+        set(PACKAGE_INFO "${download_directory}")
+      else()
+        # remove timestamps so CMake will re-download the dependency
+        file(REMOVE_RECURSE ${CMAKE_BINARY_DIR}/_deps/${lower_case_name}-subbuild)
+        set(PACKAGE_INFO "${PACKAGE_INFO} -> ${download_directory}")
+      endif()
+    endif()
+  endif()
+
+  CPM_DECLARE_PACKAGE(${CPM_ARGS_NAME} ${CPM_ARGS_VERSION} ${PACKAGE_INFO} "${CPM_ARGS_UNPARSED_ARGUMENTS}" ${FETCH_CONTENT_DECLARE_EXTRA_OPTS})
   CPM_FETCH_PACKAGE(${CPM_ARGS_NAME} ${DOWNLOAD_ONLY})
   CPMGetProperties(${CPM_ARGS_NAME})
   SET(${CPM_ARGS_NAME}_SOURCE_DIR "${${CPM_ARGS_NAME}_SOURCE_DIR}" PARENT_SCOPE)
@@ -167,8 +196,8 @@ function(CPMAddPackage)
   SET(${CPM_ARGS_NAME}_ADDED YES PARENT_SCOPE)  
 endfunction()
 
-function (CPM_DECLARE_PACKAGE PACKAGE VERSION GIT_TAG)
-  message(STATUS "${CPM_INDENT} adding package ${PACKAGE}@${VERSION} (${GIT_TAG})")
+function (CPM_DECLARE_PACKAGE PACKAGE VERSION INFO)
+  message(STATUS "${CPM_INDENT} adding package ${PACKAGE}@${VERSION} (${INFO})")
 
   if (${CPM_DRY_RUN}) 
     message(STATUS "${CPM_INDENT} package not declared (dry run)")

cmake/testing.cmake

@@ -4,7 +4,19 @@ function(ASSERT_EQUAL)
     message(FATAL_ERROR "assertion failed: invalid argument count: ${ARGC}")
   endif()
 
-  if (NOT ${ARGV0} EQUAL ${ARGV1})
+  if (NOT ${ARGV0} STREQUAL ${ARGV1})
     message(FATAL_ERROR "assertion failed: '${ARGV0}' != '${ARGV1}'")
+  else()
+    message(STATUS "test passed: '${ARGV0}' == '${ARGV1}'")
   endif()
 endfunction()
+
+function(ASSERT_EMPTY)
+  if (NOT ARGC EQUAL 0) 
+    message(FATAL_ERROR "assertion failed: input ${ARGC} not empty: '${ARGV}'")
+  endif()
+endfunction()
+
+function(ASSERTION_FAILED)
+  message(FATAL_ERROR "assertion failed: ${ARGN}")
+endfunction()

examples/benchmark/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMExampleBenchmark)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/boost/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMExampleBoost)
+
 # ---- Create binary ----
 
 add_executable(CPMExampleBoost main.cpp)

examples/build_all.py

@@ -22,7 +22,7 @@ for example in examples:
   print("running example %s" % example.name)
   print("================" + ('=' * len(example.name)))
   project = Path(".") / 'build' / example.name
-  configure = runCommand('cmake -H%s -B%s -DCMAKE_BUILD_TYPE=RelWithDebInfo' % (example, project))
+  configure = runCommand('cmake -H%s -B%s' % (example, project))
   print('  ' + '\n  '.join([line for line in configure.split('\n') if 'CPM:' in line]))
   build = runCommand('cmake --build %s -j4' % (project))
   print('  ' + '\n  '.join([line for line in build.split('\n') if 'Built target' in line]))

examples/catch2/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMExampleCatch2)
+
 # ---- Options ----
 
 option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)

examples/cxxopts/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMExampleCXXOpts)
+
 # ---- Options ----
 
 option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)

examples/doctest/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMExampleDoctest)
+
 # ---- Options ----
 
 option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)

examples/entt/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMEnTTExample)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/json/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMJSONExample)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/linenoise/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMlinenoiseExample)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/parser-lua/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
 
+project(CPMParserLuaExample)
+
 include(../../cmake/CPM.cmake)
 
 # ---- Dependencies ----

examples/parser/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
 
+project(CPMParserExample)
+
 # add dependencies
 include(../../cmake/CPM.cmake)
 

examples/range-v3/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMRangev3Example)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/simple_match/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMSimpleMatchExample)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/sol2/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMSol2Example)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)

examples/yaml/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMYamlExample)
+
 # ---- Dependencies ----
 
 include(../../cmake/CPM.cmake)
@@ -7,7 +9,7 @@ include(../../cmake/CPM.cmake)
 CPMAddPackage(
   NAME yaml-cpp
   GIT_REPOSITORY https://github.com/jbeder/yaml-cpp.git
-  # 0.6.2 uses depricated CMake syntax
+  # 0.6.2 uses deprecated CMake syntax
   VERSION 0.6.3                                  
   # 0.6.3 is not released yet, so use the most recent commit
   GIT_TAG 012269756149ae99745b6dafefd415843d7420bb 

test/CMakeLists.txt

@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
+project(CPMTests)
+
 file(GLOB tests "${CMAKE_CURRENT_SOURCE_DIR}/unit/*.cmake")
 
 enable_testing()
@@ -11,3 +13,5 @@ foreach(test ${tests})
     COMMAND ${CMAKE_COMMAND} -DCPM_PATH=${CMAKE_CURRENT_SOURCE_DIR}/../cmake -P "${test}"
   )
 endforeach()
+
+add_custom_target(test-verbose COMMAND ${CMAKE_CTEST_COMMAND} --verbose)

test/unit/cache.cmake

@@ -0,0 +1,125 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+include(${CPM_PATH}/testing.cmake)
+include(CMakePackageConfigHelpers)
+
+
+set(CPM_SOURCE_CACHE_DIR "${CMAKE_CURRENT_BINARY_DIR}/CPM")
+set(TEST_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR}/cache)
+
+function(clear_cache)
+  FILE(REMOVE_RECURSE ${CPM_SOURCE_CACHE_DIR})
+  
+  if (EXISTS "${CPM_SOURCE_CACHE_DIR}")
+    ASSERTION_FAILED("cache not cleared")
+  endif()
+endfunction()
+
+function(update_cmake_lists)
+  configure_package_config_file(
+    "${CMAKE_CURRENT_LIST_DIR}/cache/CMakeLists.txt.in"
+    "${CMAKE_CURRENT_LIST_DIR}/cache/CMakeLists.txt"
+    INSTALL_DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/junk
+  )
+endfunction()
+
+function(reset_test)
+  clear_cache()
+  FILE(REMOVE_RECURSE ${TEST_BUILD_DIR})
+  update_cmake_lists()
+endfunction()
+
+set(CATCH2_VERSION 2.8.0)
+
+## Read CPM_SOURCE_CACHE from arguments
+
+reset_test()
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/cache" "-B${TEST_BUILD_DIR}" "-DCPM_SOURCE_CACHE=${CPM_SOURCE_CACHE_DIR}"
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")
+
+if (NOT EXISTS "${CPM_SOURCE_CACHE_DIR}/catch2")
+  ASSERTION_FAILED("catch2 not in cache")
+endif()
+
+FILE(GLOB catch2_versions "${CPM_SOURCE_CACHE_DIR}/catch2/*")
+list(LENGTH catch2_versions catch2_version_count)
+ASSERT_EQUAL(${catch2_version_count} "1")
+
+FILE(GLOB fibonacci_versions "${CPM_SOURCE_CACHE_DIR}/fibonacci/*")
+list(LENGTH fibonacci_versions fibonacci_version_count)
+ASSERT_EQUAL(${fibonacci_version_count} "1")
+
+## Update dependency and keep CPM_SOURCE_CACHE
+
+set(CATCH2_VERSION 2.9.0)
+update_cmake_lists()
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} ${TEST_BUILD_DIR}
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")
+
+FILE(GLOB catch2_versions "${CPM_SOURCE_CACHE_DIR}/catch2/*")
+list(LENGTH catch2_versions catch2_version_count)
+ASSERT_EQUAL(${catch2_version_count} "2")
+
+FILE(GLOB fibonacci_versions "${CPM_SOURCE_CACHE_DIR}/fibonacci/*")
+list(LENGTH fibonacci_versions fibonacci_version_count)
+ASSERT_EQUAL(${fibonacci_version_count} "1")
+
+## Clear cache and update
+
+clear_cache()
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} ${TEST_BUILD_DIR}
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")
+
+if (NOT EXISTS "${CPM_SOURCE_CACHE_DIR}/catch2")
+  ASSERTION_FAILED("catch2 not in cache")
+endif()
+
+## Read CPM_SOURCE_CACHE from environment
+
+reset_test()
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} -E env "CPM_SOURCE_CACHE=${CPM_SOURCE_CACHE_DIR}" ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/cache" "-B${TEST_BUILD_DIR}"
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")
+
+if (NOT EXISTS "${CPM_SOURCE_CACHE_DIR}/catch2")
+  ASSERTION_FAILED("catch2 not in cache")
+endif()
+
+## Overwrite CPM_SOURCE_CACHE with argument
+
+reset_test()
+
+execute_process(
+  COMMAND 
+  ${CMAKE_COMMAND} -E env "CPM_SOURCE_CACHE=${CMAKE_CURRENT_BINARY_DIR}/junk" ${CMAKE_COMMAND} "-H${CMAKE_CURRENT_LIST_DIR}/cache" "-B${TEST_BUILD_DIR}" "-DCPM_SOURCE_CACHE=${CPM_SOURCE_CACHE_DIR}"
+  RESULT_VARIABLE ret
+)
+
+ASSERT_EQUAL(${ret} "0")
+
+if (NOT EXISTS "${CPM_SOURCE_CACHE_DIR}/catch2")
+  ASSERTION_FAILED("catch2 not in cache")
+endif()

test/unit/cache/.gitignore

@@ -0,0 +1 @@
+/CMakeLists.txt

test/unit/cache/CMakeLists.txt.in

@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPMExampleCatch2)
+
+# ---- Options ----
+
+option(ENABLE_TEST_COVERAGE "Enable test coverage" OFF)
+
+# ---- Dependencies ----
+
+include(@CPM_PATH@/CPM.cmake)
+
+CPMAddPackage(
+  NAME fibonacci
+  GIT_REPOSITORY https://github.com/TheLartians/Fibonacci.git
+  VERSION 1.0
+)
+
+CPMAddPackage(
+  NAME Catch2
+  GITHUB_REPOSITORY catchorg/Catch2
+  VERSION @CATCH2_VERSION@
+  GIT_SHALLOW YES
+)
+
+# ---- Create binary ----
+
+add_executable(CPMExampleCatch2 main.cpp)
+target_link_libraries(CPMExampleCatch2 fibonacci Catch2)
+set_target_properties(CPMExampleCatch2 PROPERTIES CXX_STANDARD 17 COMPILE_FLAGS "-Wall -pedantic -Wextra -Werror")

test/unit/cache/main.cpp

@@ -0,0 +1,13 @@
+#define CATCH_CONFIG_MAIN
+
+#include <catch2/catch.hpp>
+#include <fibonacci.h>
+
+TEST_CASE("fibonnacci"){
+  REQUIRE(fibonnacci(0) == 0);
+  REQUIRE(fibonnacci(1) == 1);
+  REQUIRE(fibonnacci(2) == 1);
+  REQUIRE(fibonnacci(3) == 2);
+  REQUIRE(fibonnacci(4) == 3);
+  REQUIRE(fibonnacci(5) == 5);
+}

test/unit/dependency_properties.cmake

@@ -10,20 +10,31 @@ CPMAddPackage(
   GIT_TAG 1.2.3
 )
 
+CPMAddPackage(
+  NAME A
+  VERSION 1.2.3
+)
+
 CPM_GET_PACKAGE_VERSION(A VERSION)
 ASSERT_EQUAL(${VERSION} "1.2.3")
 
+CPMAddPackage(
+  NAME B
+  VERSION 2.4.1
+)
+
 CPMAddPackage(
   NAME B
   GIT_TAG v2.3.1
 )
 
 CPM_GET_PACKAGE_VERSION(B VERSION)
-ASSERT_EQUAL(${VERSION} "2.3.1")
+ASSERT_EQUAL(${VERSION} "2.4.1")
 
 CPMAddPackage(
   NAME C
   GIT_TAG v3.1.2-a
+  VERSION 3.1.2
 )
 
 CPM_GET_PACKAGE_VERSION(C VERSION)