new_contents: from twisted.trial import unittest
  
  import ooni.errors
  
  class TestErrors(unittest.TestCase):
  
      def test_catch_child_failures_before_parent_failures(self):
          """
          Verify that more specific Failures are caught first by
          handleAllFailures() and failureToString().
  
          Fails if a subclass is listed after it's parent Failure.
          """
  
          # Check each Failure against all subsequent failures
          for index, (failure, _) in enumerate(ooni.errors.known_failures):
              for sub_failure, _ in ooni.errors.known_failures[index+1:]:
  
                  # Fail if subsequent Failure inherits from the current Failure
                  self.assertNotIsInstance(sub_failure(None), failure)
  
subject: Test that specific Failures are caught before parent Failures