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