Using CMake 2.8.9, building GoogleTest fails because the PROJECT_VERSION variable is required by the write_basic_config_version_file command on line 96, but it is not set for CMake versions < 3.0 on line 44 of the CMakeLists.txt. Because the version cannot be set in the project command for versions of CMake less than 3, it is possible to fix this by supplying the version explicitly to the write_basic_config_version_file command. This is shown in the following line, which allowed my project to build successfully.

  write_basic_package_version_file(${version_file} VERSION ${GOOGLETEST_VERSION} COMPATIBILITY AnyNewerVersion)