Adding tests

CMake has its own test driver program named CTest. It's easy to add new test suites to it from your CMakeLists either on your own or using the many integrations provided by testing frameworks. Later in the book, we'll discuss testing in depth, but let's first show how to quickly and cleanly add unit tests based on the GoogleTest, or GTest, testing framework.

Usually, to define your tests in CMake, you'll want to write the following:

 if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
   include(CTest)
   if(BUILD_TESTING)
     add_subdirectory(test)
   endif()
 endif()

The preceding snippet will first check whether we are the main project that's being built or not. Usually, you just want to run tests for your project and omit even building the tests for any third-party components you use. This is why the project name is checked.

If we are to run our tests, we include the CTest module. This loads the whole testing infrastructure CTest offers, defines its additional...