def test_headers(self):
        """
        Headers received by L{HTTPChannel} in a request are made available to
        the L{Request}.
        """
        processed = []
        class MyRequest(http.Request):
            def process(self):
                processed.append(self)
                self.finish()

        requestLines = [
            b"GET / HTTP/1.0",
            b"Foo: bar",
            b"baz: Quux",
            b"baz: quux",
            b"",
            b""]

        self.runRequest(b'\n'.join(requestLines), MyRequest, 0)
        [request] = processed
        self.assertEqual(
            request.requestHeaders.getRawHeaders(b'foo'), [b'bar'])
        self.assertEqual(
            request.requestHeaders.getRawHeaders(b'bAz'), [b'Quux', b'quux'])

        Headers received by L{HTTPChannel} in a request are made available to
        the L{Request}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py