Try using user@http://localhost:port for proxies

test/test_capture_http_proxy.py

@@ -29,8 +29,8 @@ def handle_error(self, request, client_address):
         server = make_server('localhost', 0, wsgiprox, server_class=NoLogServer)
         addr, cls.port = server.socket.getsockname()
 
-        cls.proxies = {'https': 'localhost:' + str(cls.port),
-                       'http': 'localhost:' + str(cls.port)
+        cls.proxies = {'https': 'http://user@localhost:' + str(cls.port),
+                       'http': 'http://user@localhost:' + str(cls.port)
                       }
 
         def run():
@@ -53,12 +53,12 @@ def test_capture_http_proxy(self):
         assert response.rec_type == 'response'
         assert response.rec_headers['WARC-Target-URI'] == "http://example.com/test"
         assert response.content_stream().read().decode('utf-8') == 'Proxied: /http://example.com/test'
-        assert response.rec_headers['WARC-Proxy-Host'] == 'http://localhost:{0}'.format(self.port)
+        assert response.rec_headers['WARC-Proxy-Host'] == 'http://user@localhost:{0}'.format(self.port)
 
         request = next(ai)
         assert request.rec_type == 'request'
         assert request.rec_headers['WARC-Target-URI'] == "http://example.com/test"
-        assert request.rec_headers['WARC-Proxy-Host'] == 'http://localhost:{0}'.format(self.port)
+        assert request.rec_headers['WARC-Proxy-Host'] == 'http://user@localhost:{0}'.format(self.port)
 
         with raises(StopIteration):
             assert next(ai)