find_package(Git) set(JSON_TEST_DATA_URL https://github.com/nlohmann/json_test_data) set(JSON_TEST_DATA_VERSION 1.0.0) # target to download test data add_custom_target(download_test_data COMMAND test -d json_test_data || ${GIT_EXECUTABLE} clone -c advice.detachedHead=false --branch v${JSON_TEST_DATA_VERSION} ${JSON_TEST_DATA_URL}.git --quiet --depth 1 COMMENT "Downloading test data from ${JSON_TEST_DATA_URL} (v${JSON_TEST_DATA_VERSION})" WORKING_DIRECTORY ${CMAKE_BINARY_DIR} ) # create a header with the path to the downloaded test data file(WRITE ${CMAKE_BINARY_DIR}/include/test_data.hpp "#define TEST_DATA_DIRECTORY \"${CMAKE_BINARY_DIR}/json_test_data\"")