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### Generic Build Instructions #### Setup To build Google Test and your tests that use it, you need to tell your build system where to find its headers and source files. The exact way to do it depends on which build system you use, and is usually straightforward. ### Build with CMake Google Test comes with a CMake build script ([CMakeLists.txt](https://github.com/google/googletest/blob/master/CMakeLists.txt)) that can be used on a wide range of platforms ("C" stands for cross-platform.). If you don't have CMake installed already, you can download it for free from <http://www.cmake.org/>. CMake works by generating native makefiles or build projects that can be used in the compiler environment of your choice. You can either build Google Test as a standalone project or it can be incorporated into an existing CMake build for another project. #### Standalone CMake Project When building Google Test as a standalone project, the typical workflow starts with: mkdir mybuild # Create a directory to hold the build output. cd mybuild cmake ${GTEST_DIR} # Generate native build scripts. If you want to build Google Test's samples, you should replace the last command with cmake -Dgtest_build_samples=ON ${GTEST_DIR} If you are on a \*nix system, you should now see a Makefile in the current directory. Just type 'make' to build gtest. If you use Windows and have Visual Studio installed, a `gtest.sln` file and several `.vcproj` files will be created. You can then build them using Visual Studio. On Mac OS X with Xcode installed, a `.xcodeproj` file will be generated. #### Incorporating Into An Existing CMake Project If you want to use gtest in a project which already uses CMake, then a more robust and flexible approach is to build gtest as part of that project directly. This is done by making the GoogleTest source code available to the main build and adding it using CMake's `add_subdirectory()` command. This has the significant advantage that the same compiler and linker settings are used between gtest and the rest of your project, so issues associated with using incompatible libraries (eg debug/release), etc. are avoided. This is particularly useful on Windows. Making GoogleTest's source code available to the main build can be done a few different ways: * Download the GoogleTest source code manually and place it at a known location. This is the least flexible approach and can make it more difficult to use with continuous integration systems, etc. * Embed the GoogleTest source code as a direct copy in the main project's source tree. This is often the simplest approach, but is also the hardest to keep up to date. Some organizations may not permit this method. * Add GoogleTest as a git submodule or equivalent. This may not always be possible or appropriate. Git submodules, for example, have their own set of advantages and drawbacks. * Use CMake to download GoogleTest as part of the build's configure step. This is just a little more complex, but doesn't have the limitations of the other methods. The last of the above methods is implemented with a small piece of CMake code in a separate file (e.g. `CMakeLists.txt.in`) which is copied to the build area and then invoked as a sub-build _during the CMake stage_. That directory is then pulled into the main build with `add_subdirectory()`. For example: New file `CMakeLists.txt.in`: ```cmake cmake_minimum_required(VERSION 2.8.2) project(googletest-download NONE) include(ExternalProject) ExternalProject_Add(googletest GIT_REPOSITORY https://github.com/google/googletest.git GIT_TAG master SOURCE_DIR "${CMAKE_CURRENT_BINARY_DIR}/googletest-src" BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/googletest-build" CONFIGURE_COMMAND "" BUILD_COMMAND "" INSTALL_COMMAND "" TEST_COMMAND "" ) ``` Existing build's `CMakeLists.txt`: ```cmake # Download and unpack googletest at configure time configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt) execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" . RESULT_VARIABLE result WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download ) if(result) message(FATAL_ERROR "CMake step for googletest failed: ${result}") endif() execute_process(COMMAND ${CMAKE_COMMAND} --build . RESULT_VARIABLE result WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download ) if(result) message(FATAL_ERROR "Build step for googletest failed: ${result}") endif() # Prevent overriding the parent project's compiler/linker # settings on Windows set(gtest_force_shared_crt ON CACHE BOOL "" FORCE) # Add googletest directly to our build. This defines # the gtest and gtest_main targets. add_subdirectory(${CMAKE_CURRENT_BINARY_DIR}/googletest-src ${CMAKE_CURRENT_BINARY_DIR}/googletest-build EXCLUDE_FROM_ALL) # The gtest/gtest_main targets carry header search path # dependencies automatically when using CMake 2.8.11 or # later. Otherwise we have to add them here ourselves. if (CMAKE_VERSION VERSION_LESS 2.8.11) include_directories("${gtest_SOURCE_DIR}/include") endif() # Now simply link against gtest or gtest_main as needed. Eg add_executable(example example.cpp) target_link_libraries(example gtest_main) add_test(NAME example_test COMMAND example) ``` Note that this approach requires CMake 2.8.2 or later due to its use of the `ExternalProject_Add()` command. The above technique is discussed in more detail in [this separate article](http://crascit.com/2015/07/25/cmake-gtest/) which also contains a link to a fully generalized implementation of the technique. ##### Visual Studio Dynamic vs Static Runtimes By default, new Visual Studio projects link the C runtimes dynamically but Google Test links them statically. This will generate an error that looks something like the following: gtest.lib(gtest-all.obj) : error LNK2038: mismatch detected for 'RuntimeLibrary': value 'MTd_StaticDebug' doesn't match value 'MDd_DynamicDebug' in main.obj Google Test already has a CMake option for this: `gtest_force_shared_crt` Enabling this option will make gtest link the runtimes dynamically too, and match the project in which it is included. #### C++ Standard Version An environment that supports C++11 is required in order to successfully build Google Test. One way to ensure this is to specify the standard in the top-level project, for example by using the `set(CMAKE_CXX_STANDARD 11)` command. If this is not feasible, for example in a C project using Google Test for validation, then it can be specified by adding it to the options for cmake via the `DCMAKE_CXX_FLAGS` option. ### Tweaking Google Test Google Test can be used in diverse environments. The default configuration may not work (or may not work well) out of the box in some environments. However, you can easily tweak Google Test by defining control macros on the compiler command line. Generally, these macros are named like `GTEST_XYZ` and you define them to either 1 or 0 to enable or disable a certain feature. We list the most frequently used macros below. For a complete list, see file [include/gtest/internal/gtest-port.h](https://github.com/google/googletest/blob/master/googletest/include/gtest/internal/gtest-port.h). ### Multi-threaded Tests Google Test is thread-safe where the pthread library is available. After `#include "gtest/gtest.h"`, you can check the `GTEST_IS_THREADSAFE` macro to see whether this is the case (yes if the macro is `#defined` to 1, no if it's undefined.). If Google Test doesn't correctly detect whether pthread is available in your environment, you can force it with -DGTEST_HAS_PTHREAD=1 or -DGTEST_HAS_PTHREAD=0 When Google Test uses pthread, you may need to add flags to your compiler and/or linker to select the pthread library, or you'll get link errors. If you use the CMake script, this is taken care of for you. If you use your own