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diff --git a/third_party/googletest/googletest/README.md b/third_party/googletest/googletest/README.md new file mode 100644 index 0000000000..8760d13edc --- /dev/null +++ b/third_party/googletest/googletest/README.md @@ -0,0 +1,217 @@ +### 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](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 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-1.12.0 +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`: + +```cmake +include(FetchContent) +FetchContent_Declare( + googletest + # Specify the commit you depend on and update it regularly. + URL https://github.com/google/googletest/archive/5376968f6948923e2411081fd9372e71a59d8e77.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](https://github.com/google/googletest/blob/master/googletest/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 `ASSERT_EQ`, `ASSERT_FALSE`, `ASSERT_GE`, +`ASSERT_GT`, `ASSERT_LE`, `ASSERT_LT`, `ASSERT_NE`, `ASSERT_TRUE`, +`EXPECT_FALSE`, `EXPECT_TRUE`, `FAIL`, `SUCCEED`, `TEST`, or `TEST_F`. 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. |