Falderal Test: err-no-stderr
When running a failing test, if the implementation finished with a failing
exit code, but did not provide anything on stderr, expect the error message
to be on stdout.
-> Functionality "Error on stdout" is implemented by shell command
-> "python3 fail.py %(test-body-text) '' 1"
-> Tests for functionality "Error on stdout"
| this is the error message
? this is the error message