Tests/FindPackageCpsTest/requires-test.cxx - third_party/github.com/Kitware/CMake - Git at Google

 #ifndef ANSWER
 #  error ANSWER is not defined
 #else
 #  if ANSWER != 42
 #    error ANSWER has the wrong value
 #  endif
 #endif
	#ifndef ANSWER
	# error ANSWER is not defined
	#else
	# if ANSWER != 42
	# error ANSWER has the wrong value
	# endif
	#endif