Receive notifications during unit tests with XCTest?

In the old SenTestingKit we used to get some really useful notifications while the tests were running:

SenTestSuiteDidStartNotification
SenTestSuiteDidStopNotification
SenTestCaseDidStartNotification
SenTestCaseDidStopNotification
SenTestCaseDidFailNotification

These would also contain information about the tests/suites such as the name and failure description for failures.

These days, XCTest is the recommended way to do unit testing, I found that there was something called XCTestObserver, but it is already deprecated. So how can I monitor the progress of unit tests based on XCTest?