def assertMistakenMethodWarning(self, resultList):
        """
        Flush the current warnings and assert that we have been told that
        C{mistakenMethod} was invoked, and that the result from the Deferred
        that was fired (appended to the given list) is C{mistakenMethod}'s
        result.  The warning should indicate that an inlineCallbacks function
        called 'inline' was made to exit.
        """
        self.assertEqual(resultList, [1])
        warnings = self.flushWarnings(offendingFunctions=[self.mistakenMethod])
        self.assertEqual(len(warnings), 1)
        self.assertEqual(warnings[0]['category'], DeprecationWarning)
        self.assertEqual(
            warnings[0]['message'],
            "returnValue() in 'mistakenMethod' causing 'inline' to exit: "
            "returnValue should only be invoked by functions decorated with "
            "inlineCallbacks")

        Flush the current warnings and assert that we have been told that
        C{mistakenMethod} was invoked, and that the result from the Deferred
        that was fired (appended to the given list) is C{mistakenMethod}'s
        result.  The warning should indicate that an inlineCallbacks function
        called 'inline' was made to exit.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_inlinecb.py