def test_missingDocumentFactory(self):
        def cb(ignored):
            # The old flattener unconditionally logs errors.
            self.flushLoggedErrors(MissingDocumentFactory)
        d = self.assertFailure(self._render(Element()), FlattenerError)
        d.addCallback(cb)
        return d
Test that rendering a Element without a docFactory attribute raises
dataset/ETHPy150Open twisted/nevow/nevow/test/test_element.py/FlattenIntegrationTests.test_missingDocumentFactory