Test the interaction between trial and errors logged during test run.
| Function | makeFailure | Return a new, realistic failure. | 
| Class | Mask | Hide MockTests from Trial's automatic test finder. | 
| Class | ObserverTests | Tests for _synctest._LogObserver,
a helper for the implementation ofSynchronousTestCase.flushLoggedErrors. | 
| Class | LogErrorsMixin | High-level tests demonstrating the expected behaviour of logged errors during tests. | 
| Class | SynchronousLogErrorsTests | Undocumented | 
| Class | AsynchronousLogErrorsTests | No class docstring; 1/1 methods documented |