cmake: Incorporate gtest in a standard way

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.6)
+cmake_minimum_required(VERSION 2.8.2)
 project(libmc)
 set(CMAKE_MACOSX_RPATH 1)
 
@@ -48,8 +48,39 @@ install(
 
 option(WITH_TESTING "Enable testing" OFF)
 if (WITH_TESTING)
-    set(EXT_PROJECTS_DIR ${CMAKE_SOURCE_DIR}/ext)
-    add_subdirectory(${EXT_PROJECTS_DIR}/gtest)
+    # Download and unpack googletest at configure time
+    configure_file(ext/gtest/CMakeLists.txt.in ext/gtest/CMakeLists.txt)
+    execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
+      RESULT_VARIABLE result
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/ext/gtest )
+    if(result)
+      message(FATAL_ERROR "CMake step for googletest failed: ${result}")
+    endif()
+    execute_process(COMMAND ${CMAKE_COMMAND} --build .
+      RESULT_VARIABLE result
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/ext/gtest )
+    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_BINARY_DIR}/googletest-src
+                     ${CMAKE_BINARY_DIR}/googletest-build
+                     EXCLUDE_FROM_ALL)
+
+    # The gtest/gtest_main targets carry header search path
+    # dependencies automatically when using CMake 2.8.11 or
+    # later. Otherwise we have to add them here ourselves.
+    if (CMAKE_VERSION VERSION_LESS 2.8.11)
+      include_directories("${gtest_SOURCE_DIR}/include")
+    endif()
+
+    # Now simply link against gtest or gtest_main as needed. Eg
     enable_testing()
     add_subdirectory(tests)
 endif (WITH_TESTING)

ext/gtest/CMakeLists.txt.in

@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 2.8.2)
+project(gtest_builder C CXX)
+
+include(ExternalProject)
+
+ExternalProject_Add(googletest
+    GIT_REPOSITORY https://github.com/google/googletest.git
+    GIT_TAG master
+    SOURCE_DIR "${CMAKE_BINARY_DIR}/googletest-src"
+    BINARY_DIR "${CMAKE_BINARY_DIR}/googletest-build"
+    CMAKE_ARGS -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY_DEBUG:PATH=DebugLibs
+               -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY_RELEASE:PATH=ReleaseLibs
+    CONFIGURE_COMMAND ""
+    BUILD_COMMAND ""
+    INSTALL_COMMAND ""
+    TEST_COMMAND ""
+)

tests/CMakeLists.txt

@@ -1,14 +1,12 @@
-include_directories(${GTEST_INCLUDE_DIRS})
 file(GLOB TEST_SRC_FILES ${PROJECT_SOURCE_DIR}/tests/test_*.cpp)
 
 foreach(SRC ${TEST_SRC_FILES})
     get_filename_component(test_name ${SRC} NAME_WE)
     set_source_files_properties(${SRC} PROPERTIES COMPILE_FLAGS "-fexceptions")
     add_executable(${test_name} ${SRC})
-    add_dependencies(${test_name} googletest)
+    add_dependencies(${test_name} gtest)
     target_link_libraries(${test_name}
-        ${GTEST_LIBS_DIR}/libgtest.a
-        ${GTEST_LIBS_DIR}/libgtest_main.a
+        gtest_main
         pthread
         mc
         )