message: export Mocks.h file for tests in dependent projects
  Summary: ^
diff: # Always install this header, even when not building tests.
  # It can be used by dependent projects to build their own tests
  -install(FILES MockQuicSocket.h DESTINATION include/quic/api/test)
  +install(FILES MockQuicSocket.h Mocks.h DESTINATION include/quic/api/test)
  if(NOT BUILD_TESTS)
  return()
  