Collects the failure text that would be printed instead of printing it, and does not count the
failures against the run: for tests of the test tools themselves. end_failure_capture
returns the text and how many failures there were.
begin_failure_capture :: ()
Collects the failure text that would be printed instead of printing it, and does not count the
failures against the run: for tests of the test tools themselves. end_failure_capture
returns the text and how many failures there were.