Return true if code fails with an error message matching pattern, otherwise produce an error. Note that code is a string and if code runs successfully, the error produced is:
expected error but got noneIf the code fails with a different error, the message produced is:
expected <pattern> but got <text of actual error>The angle brackets are not part of the output.
Called with three arguments, the behavior is similar to
fail(
code,
pattern)
, but produces an error if no warning is given during code execution or if the code fails.