def test_headersCleanups(self):
        client = ProxyClient(b'GET', b'/foo', b'HTTP/1.0',
            {b"accept": b"text/html", b"proxy-connection": b"foo"}, b'', None)
        self.assertEqual(client.headers,
            {b"accept": b"text/html", b"connection": b"close"})
The headers given at initialization should be modified:
dataset/ETHPy150Open twisted/twisted/twisted/web/test/test_proxy.py/ProxyClientTests.test_headersCleanups