1## Using GoogleTest from various build systems 2 3GoogleTest comes with pkg-config files that can be used to determine all 4necessary flags for compiling and linking to GoogleTest (and GoogleMock). 5Pkg-config is a standardised plain-text format containing 6 7* the includedir (-I) path 8* necessary macro (-D) definitions 9* further required flags (-pthread) 10* the library (-L) path 11* the library (-l) to link to 12 13All current build systems support pkg-config in one way or another. For all 14examples here we assume you want to compile the sample 15`samples/sample3_unittest.cc`. 16 17### CMake 18 19Using `pkg-config` in CMake is fairly easy: 20 21```cmake 22cmake_minimum_required(VERSION 3.0) 23 24cmake_policy(SET CMP0048 NEW) 25project(my_gtest_pkgconfig VERSION 0.0.1 LANGUAGES CXX) 26 27find_package(PkgConfig) 28pkg_search_module(GTEST REQUIRED gtest_main) 29 30add_executable(testapp samples/sample3_unittest.cc) 31target_link_libraries(testapp ${GTEST_LDFLAGS}) 32target_compile_options(testapp PUBLIC ${GTEST_CFLAGS}) 33 34include(CTest) 35add_test(first_and_only_test testapp) 36``` 37 38It is generally recommended that you use `target_compile_options` + `_CFLAGS` 39over `target_include_directories` + `_INCLUDE_DIRS` as the former includes not 40just -I flags (GoogleTest might require a macro indicating to internal headers 41that all libraries have been compiled with threading enabled. In addition, 42GoogleTest might also require `-pthread` in the compiling step, and as such 43splitting the pkg-config `Cflags` variable into include dirs and macros for 44`target_compile_definitions()` might still miss this). The same recommendation 45goes for using `_LDFLAGS` over the more commonplace `_LIBRARIES`, which happens 46to discard `-L` flags and `-pthread`. 47 48### Autotools 49 50Finding GoogleTest in Autoconf and using it from Automake is also fairly easy: 51 52In your `configure.ac`: 53 54``` 55AC_PREREQ([2.69]) 56AC_INIT([my_gtest_pkgconfig], [0.0.1]) 57AC_CONFIG_SRCDIR([samples/sample3_unittest.cc]) 58AC_PROG_CXX 59 60PKG_CHECK_MODULES([GTEST], [gtest_main]) 61 62AM_INIT_AUTOMAKE([foreign subdir-objects]) 63AC_CONFIG_FILES([Makefile]) 64AC_OUTPUT 65``` 66 67and in your `Makefile.am`: 68 69``` 70check_PROGRAMS = testapp 71TESTS = $(check_PROGRAMS) 72 73testapp_SOURCES = samples/sample3_unittest.cc 74testapp_CXXFLAGS = $(GTEST_CFLAGS) 75testapp_LDADD = $(GTEST_LIBS) 76``` 77 78### Meson 79 80Meson natively uses pkgconfig to query dependencies: 81 82``` 83project('my_gtest_pkgconfig', 'cpp', version : '0.0.1') 84 85gtest_dep = dependency('gtest_main') 86 87testapp = executable( 88 'testapp', 89 files(['samples/sample3_unittest.cc']), 90 dependencies : gtest_dep, 91 install : false) 92 93test('first_and_only_test', testapp) 94``` 95 96### Plain Makefiles 97 98Since `pkg-config` is a small Unix command-line utility, it can be used in 99handwritten `Makefile`s too: 100 101```makefile 102GTEST_CFLAGS = `pkg-config --cflags gtest_main` 103GTEST_LIBS = `pkg-config --libs gtest_main` 104 105.PHONY: tests all 106 107tests: all 108 ./testapp 109 110all: testapp 111 112testapp: testapp.o 113 $(CXX) $(CXXFLAGS) $(LDFLAGS) $< -o $@ $(GTEST_LIBS) 114 115testapp.o: samples/sample3_unittest.cc 116 $(CXX) $(CPPFLAGS) $(CXXFLAGS) $< -c -o $@ $(GTEST_CFLAGS) 117``` 118 119### Help! pkg-config can't find GoogleTest! 120 121Let's say you have a `CMakeLists.txt` along the lines of the one in this 122tutorial and you try to run `cmake`. It is very possible that you get a failure 123along the lines of: 124 125``` 126-- Checking for one of the modules 'gtest_main' 127CMake Error at /usr/share/cmake/Modules/FindPkgConfig.cmake:640 (message): 128 None of the required 'gtest_main' found 129``` 130 131These failures are common if you installed GoogleTest yourself and have not 132sourced it from a distro or other package manager. If so, you need to tell 133pkg-config where it can find the `.pc` files containing the information. Say you 134installed GoogleTest to `/usr/local`, then it might be that the `.pc` files are 135installed under `/usr/local/lib64/pkgconfig`. If you set 136 137``` 138export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig 139``` 140 141pkg-config will also try to look in `PKG_CONFIG_PATH` to find `gtest_main.pc`. 142