Marks all tests in the given test suite as expected failures: The tests will still be run, but if they succeed, it is reported as a test suite failure, and conversely a the failure of the test is ignored.
Any output of a failing test is still printed.
This is useful if, in a test driven development, tests are written and commited to the master branch before their implementation: It allows the tests to fail (as expected) without making the whole test suite fail.
Similarly, regressions and bugs can be documented in the test suite this way, until a fix is commited, and if a fix is applied (intentionally or accidentially), the test suite will remind you to remove the expectFail marker.