Use these expectations to test other expectations.
Use show_failure() in examples to print the failure message without
throwing an error.
expect_success(expr)expect_failure(expr, message = NULL, ...)
show_failure(expr)
expect_known_failure(path, expr)
Expression that evaluates a single expectation.
Check that the failure message matches this regexp.
Other arguments passed on to expect_match().
Path to save failure output