diff --git a/jupyterhub/tests/mocksu.py b/jupyterhub/tests/mocksu.py
new file mode 100644
index 00000000..e770c146
--- /dev/null
+++ b/jupyterhub/tests/mocksu.py
@@ -0,0 +1,40 @@
+"""Mock single-user server for testing
+
+basic HTTP Server that echos URLs back,
+and allow retrieval of sys.argv.
+"""
+
+import argparse
+import json
+import sys
+
+from tornado import web, httpserver, ioloop
+
+
+class EchoHandler(web.RequestHandler):
+    def get(self):
+        self.write(self.request.path)
+
+class ArgsHandler(web.RequestHandler):
+    def get(self):
+        self.write(json.dumps(sys.argv))
+
+def main(args):
+    
+    app = web.Application([
+        (r'.*/args', ArgsHandler),
+        (r'.*', EchoHandler),
+    ])
+    
+    server = httpserver.HTTPServer(app)
+    server.listen(args.port)
+    try:
+        ioloop.IOLoop.instance().start()
+    except KeyboardInterrupt:
+        print('\nInterrupted')
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--port', type=int)
+    args, extra = parser.parse_known_args()
+    main(args)
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