diff -rNu test_server-0.0.31.old/test_server/server.py test_server-0.0.31/test_server/server.py
--- test_server-0.0.31.old/test_server/server.py	2018-05-05 20:01:28.000000000 +0200
+++ test_server-0.0.31/test_server/server.py	2018-11-01 21:58:26.331632215 +0100
@@ -227,7 +227,14 @@
 
 
 class TestServer(object):
-    def __init__(self, port=0, address='127.0.0.1'):
+    def __init__(self, port=0, address='127.0.0.1', engine=None):
+        if engine:
+            # be nice to expectations of old API
+            import warnings
+            text = "value of parameter engine is ignored with version 0.0.31"
+            text += " and param might get removed later"
+            warnings.warn(text, DeprecationWarning)
+
         self.request = {}
         self.response = {}
         self.response_once = {}