anchor.diff:      Transport = proplists:get_value(transport, Props, tcp),
       IsLegacy = proplists:get_value(wslegacy, Props, false),
       StreamStartReq = case {Transport, IsLegacy} of
  -                         {ws, false} -> escalus_stanza:ws_open(Server);
  +                         {escalus_ws, false} -> escalus_stanza:ws_open(Server);
                            _ -> escalus_stanza:stream_start(Server, NS)
                        end,
       ok = escalus_connection:send(Conn, StreamStartReq),
  
positive.code: 
  assert_stream_start(StreamStartRep, Transport, IsLegacy) ->
      case {StreamStartRep, Transport, IsLegacy} of
          {#xmlel{name = <<"open">>}, ws, false} ->
              ok;
          {#xmlel{name = <<"open">>}, ws, true} ->
              error("<open/> with legacy WebSocket",
                    [StreamStartRep]);
          {#xmlstreamstart{}, ws, false} ->
              error("<stream:stream> with non-legacy WebSocket",
                    [StreamStartRep]);
          {#xmlstreamstart{}, _, _} ->
  
negative.code: 
  assert_stream_features(StreamFeatures, Transport, IsLegacy) ->
      case {StreamFeatures, Transport, IsLegacy} of
          {#xmlel{name = <<"features">>}, escalus_ws, false} ->
              ok;
          {#xmlel{name = <<"features">>}, escalus_ws, true} ->
              error("<features> with legacy WebSocket");
          {#xmlel{name = <<"stream:features">>}, escalus_ws, false} ->
              error("<stream:features> with non-legacy WebSocket",
                    [StreamFeatures]);
          {#xmlel{name = <<"stream:features">>}, _, _} ->
  