def test_renderWithUnknownHost(self):
        """
        L{NameVirtualHost.render} returns the result of rendering the
        instance's C{default} if it is not L{None} and there is no host
        matching the value of the I{Host} header in the request.
        """
        virtualHostResource = NameVirtualHost()
        virtualHostResource.default = Data(b"correct data", "")
        request = DummyRequest([b''])
        request.requestHeaders.addRawHeader(b'host', b'example.com')
        d = _render(virtualHostResource, request)
        def cbRendered(ignored):
            self.assertEqual(b''.join(request.written), b"correct data")
        d.addCallback(cbRendered)
        return d

        L{NameVirtualHost.render} returns the result of rendering the
        instance's C{default} if it is not L{None} and there is no host
        matching the value of the I{Host} header in the request.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_vhost.py