Tests/RunCMake/FASTBuild/UnityGroup.cmake

set(CMAKE_UNITY_BUILD ON)
add_executable(main main.cpp some_source_file_1.cpp some_source_file_2.cpp)

set_source_files_properties(
    some_source_file_1.cpp
    some_source_file_2.cpp

    TARGET_DIRECTORY
        main
    PROPERTIES
        UNITY_GROUP "TestGroup"
)