def test_missingRenderMethod(self):
        """
        Flattening an L{Element} with a C{loader} which has a tag with a render
        directive fails with L{FlattenerError} if there is no available render
        method to satisfy that directive.
        """
        element = Element(loader=XMLString("""
        <p xmlns:t="http://twistedmatrix.com/ns/twisted.web.template/0.1"
          t:render="unknownMethod" />
        """))
        return self.assertFlatteningRaises(element, MissingRenderMethod)

        Flattening an L{Element} with a C{loader} which has a tag with a render
        directive fails with L{FlattenerError} if there is no available render
        method to satisfy that directive.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_template.py