Idea Summary
When using apex_error.have_errors_occurred for unit testing the error stack is not able to be cleared. This means that when checking apex_error for failed unit tests it will keep finding an issue because some other test logged an error.

Use Case
When using utPLSQL and checking the apex_error.have_errors_occurred or apex_error.get_error_count (on the database, not in the Apex environment) it will report errors and there is no way to clear the error stack until the session is disconnected.

Preferred Solution (Optional)
Add something like apex_error.clear_error_stack.