Tempest_in_Action/yaml-cpp/test/gtest-1.11.0/googletest

Generic Build Instructions

Setup

To build GoogleTest 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

GoogleTest comes with a CMake build script (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 GoogleTest as a standalone project or it can be incorporated into an existing CMake build for another project.

Standalone CMake Project

When building GoogleTest as a standalone project, the typical workflow starts with

git clone https://github.com/google/googletest.git -b release-1.10.0
cd googletest        # Main directory of the cloned repository.
mkdir build          # Create a directory to hold the build output.
cd build
cmake ..             # Generate native build scripts for GoogleTest.

The above command also includes GoogleMock by default. And so, if you want to build only GoogleTest, you should replace the last command with

cmake .. -DBUILD_GMOCK=OFF

If you are on a *nix system, you should now see a Makefile in the current directory. Just type make to build GoogleTest. And then you can simply install GoogleTest if you are a system administrator.

make
sudo make install    # Install in /usr/local/ by default

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 GoogleTest in a project which already uses CMake, the easiest way is to get installed libraries and headers.

• Import GoogleTest by using find_package (or pkg_check_modules). For example, if find_package(GTest CONFIG REQUIRED) succeeds, you can use the libraries as GTest::gtest, GTest::gmock.

And a more robust and flexible approach is to build GoogleTest 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 GoogleTest 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 approach doesn't have the limitations of the other methods.

The last of the above methods is implemented with a small piece of CMake code that downloads and pulls the GoogleTest code into the main build.

Just add to your CMakeLists.txt:

include(FetchContent)
FetchContent_Declare(
  googletest
  # Specify the commit you depend on and update it regularly.
  URL https://github.com/google/googletest/archive/609281088cfefc76f9d0ce82e1ff6c30cc3591e5.zip
)
# For Windows: Prevent overriding the parent project's compiler/linker settings
set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
FetchContent_MakeAvailable(googletest)

# 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 3.14 or later due to its use of the FetchContent_MakeAvailable() command.

Visual Studio Dynamic vs Static Runtimes

By default, new Visual Studio projects link the C runtimes dynamically but GoogleTest 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

GoogleTest 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 GoogleTest. 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 GoogleTest for validation, then it can be specified by adding it to the options for cmake via the DCMAKE_CXX_FLAGS option.

Tweaking GoogleTest

GoogleTest 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 GoogleTest 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.

Multi-threaded Tests

GoogleTest 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 GoogleTest 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 GoogleTest 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 build script, you'll need to read your compiler and linker's manual to figure out what flags to add.

As a Shared Library (DLL)

GoogleTest is compact, so most users can build and link it as a static library for the simplicity. You can choose to use GoogleTest as a shared library (known as a DLL on Windows) if you prefer.

To compile gtest as a shared library, add

-DGTEST_CREATE_SHARED_LIBRARY=1

to the compiler flags. You'll also need to tell the linker to produce a shared library instead - consult your linker's manual for how to do it.

To compile your tests that use the gtest shared library, add

-DGTEST_LINKED_AS_SHARED_LIBRARY=1

to the compiler flags.

Note: while the above steps aren't technically necessary today when using some compilers (e.g. GCC), they may become necessary in the future, if we decide to improve the speed of loading the library (see http://gcc.gnu.org/wiki/Visibility for details). Therefore you are recommended to always add the above flags when using GoogleTest as a shared library. Otherwise a future release of GoogleTest may break your build script.

Avoiding Macro Name Clashes

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 GoogleTest macro clashes with another library, you can force GoogleTest to rename its macro to avoid the conflict.

Specifically, if both GoogleTest and some other code define macro FOO, you can add

-DGTEST_DONT_DEFINE_FOO=1

to the compiler flags to tell GoogleTest to change the macro's name from FOO to GTEST_FOO. Currently FOO can be FAIL, SUCCEED, or TEST. For example, with -DGTEST_DONT_DEFINE_TEST=1, you'll need to write

GTEST_TEST(SomeTest, DoesThis) { ... }

instead of

TEST(SomeTest, DoesThis) { ... }

in order to define a test.