Adding configurations for gtest

if (NOT TARGET gtest)

  set(GOOGLETEST_ROOT gtest/googletest CACHE STRING "Google Test source root")

  include_directories(SYSTEM

      ${PROJECT_SOURCE_DIR}/${GOOGLETEST_ROOT}

      ${PROJECT_SOURCE_DIR}/${GOOGLETEST_ROOT}/include

      )

  set(GOOGLETEST_SOURCES

      ${PROJECT_SOURCE_DIR}/${GOOGLETEST_ROOT}/src/gtest-all.cc

      ${PROJECT_SOURCE_DIR}/${GOOGLETEST_ROOT}/src/gtest_main.cc

      )

  foreach(_source ${GOOGLETEST_SOURCES})

      set_source_files_properties(${_source} PROPERTIES GENERATED 1)

  endforeach()

  add_library(gtest ${GOOGLETEST_SOURCES})

endif()