def test_sendHeaderSanitizesLinearWhitespace(self):
        """
        L{HTTPClient.sendHeader} replaces linear whitespace in its
        header keys and values with a single space.
        """
        for component in bytesLinearWhitespaceComponents:
            transport = StringTransport()
            client = http.HTTPClient()
            client.makeConnection(transport)
            client.sendHeader(component, component)
            self.assertEqual(
                transport.value().splitlines(),
                [b": ".join([sanitizedBytes, sanitizedBytes])]
            )

        L{HTTPClient.sendHeader} replaces linear whitespace in its
        header keys and values with a single space.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py