Bug 1020024 - fix data channel connecting race conditions. r=jib

dom/media/tests/mochitest/pc.js

@@ -1119,23 +1119,17 @@ DataChannelTest.prototype = Object.create(PeerConnectionTest.prototype, {
      */
     value : function DCT_waitForInitialDataChannel(peer, onSuccess, onFailure) {
       var dcConnectionTimeout = null;
+      var dcOpened = false;
 
       function dataChannelConnected(channel) {
+        // in case the switch statement below had called onSuccess already we
+        // don't want to call it again
+        if (!dcOpened) {
           clearTimeout(dcConnectionTimeout);
           is(channel.readyState, "open", peer + " dataChannels[0] switched to state: 'open'");
+          dcOpened = true;
           onSuccess();
         }
-
-      if (peer.dataChannels.length >= 1) {
-        if (peer.dataChannels[0].readyState === "open") {
-          is(peer.dataChannels[0].readyState, "open", peer + " dataChannels[0] is already in state: 'open'");
-          onSuccess();
-          return;
-        } else {
-          is(peer.dataChannels[0].readyState, "connecting", peer + " dataChannels[0] is in state: 'connecting'");
-        }
-      } else {
-        info(peer + "'s dataChannels[] is empty");
       }
 
       // TODO: drno: convert dataChannels into an object and make
@@ -1146,12 +1140,34 @@ DataChannelTest.prototype = Object.create(PeerConnectionTest.prototype, {
         peer.registerDataChannelOpenEvents(dataChannelConnected);
       }
 
+      if (peer.dataChannels.length >= 1) {
+        // snapshot of the live value as it might change during test execution
+        const readyState = peer.dataChannels[0].readyState;
+        switch (readyState) {
+          case "open": {
+            is(readyState, "open", peer + " dataChannels[0] is already in state: 'open'");
+            dcOpened = true;
+            onSuccess();
+            break;
+          }
+          case "connecting": {
+            is(readyState, "connecting", peer + " dataChannels[0] is in state: 'connecting'");
             if (onFailure) {
               dcConnectionTimeout = setTimeout(function () {
-          info(peer + " timed out while waiting for dataChannels[0] to connect");
+                is(peer.dataChannels[0].readyState, "open", peer + " timed out while waiting for dataChannels[0] to open");
                 onFailure();
               }, 60000);
             }
+            break;
+          }
+          default: {
+            ok(false, "dataChannels[0] is in unexpected state " + readyState);
+            if (onFailure) {
+              onFailure()
+            }
+          }
+        }
+      }
     }
   }