Add FAIL macros

[Warwolt]

It would be convenient to be able to immediately fail a test

if (some_condition) {
    FAIL_INFO("Some specific unexpected situation happened!");
}

Google Test has:

FAIL(); // fatal
ADD_FAILURE(); // non-fatal
SUCCESS(); // does nothing, just for documentation

https://google.github.io/googletest/reference/assertions.html#success-failure