Espresso test for loopback video quality testing

webrtc/examples/androidapp/src/org/appspot/apprtc/RoomParametersFetcher.java

 /*
  *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 121 matching lines @@
           iceServersFromPCConfigJSON(roomJson.getString("pc_config"));
       boolean isTurnPresent = false;
       for (PeerConnection.IceServer server : iceServers) {
         Log.d(TAG, "IceServer: " + server);
         if (server.uri.startsWith("turn:")) {
           isTurnPresent = true;
           break;
         }
       }
       // Request TURN servers.
-      if (!isTurnPresent) {
+      if (!isTurnPresent && roomJson.has("ice_server_url")) {
         LinkedList<PeerConnection.IceServer> turnServers =
             requestTurnServers(roomJson.getString("ice_server_url"));
         for (PeerConnection.IceServer turnServer : turnServers) {
           Log.d(TAG, "TurnServer: " + turnServer);
           iceServers.add(turnServer);
         }
       }
 
       SignalingParameters params = new SignalingParameters(
           iceServers, initiator, clientId, wssUrl, wssPostUrl, offerSdp, iceCandidates);
@@ skipping 55 matching lines @@
     }
     return ret;
   }
 
   // Return the contents of an InputStream as a String.
   private static String drainStream(InputStream in) {
     Scanner s = new Scanner(in).useDelimiter("\\A");
     return s.hasNext() ? s.next() : "";
   }
 }