def test_missingDocumentFactory(self):
        element = Element()
        err = self.assertRaises(MissingDocumentFactory, element.render, None)
        self.assertIdentical(err.element, element)
L{Element.render} raises L{MissingDocumentFactory} if the C{docFactory}
dataset/ETHPy150Open twisted/nevow/nevow/test/test_element.py/ElementTests.test_missingDocumentFactory