Part 0: Test-case for bug.

Differential Revision: https://phabricator.services.mozilla.com/D30990

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1550177
gecko-commit: 1ff47be3226505205ae2357777a80953f56e06bb
gecko-integration-branch: central
gecko-reviewers: jib

webrtc/RTCPeerConnection-iceGatheringState.html

@@ -60,16 +60,21 @@
 
     t.add_cleanup(() => pc.close());
 
+    let reachedGathering = false;
     const onIceGatheringStateChange = t.step_func(() => {
       const { iceGatheringState } = pc;
 
-      if(iceGatheringState === 'complete') {
+      if(iceGatheringState === 'gathering') {
+        reachedGathering = true;
+      } else if(iceGatheringState === 'complete') {
+        assert_true(reachedGathering, 'iceGatheringState should reach gathering before complete');
         t.done();
       }
     });
 
     assert_equals(pc.onicegatheringstatechange, null,
       'Expect connection to have icegatheringstatechange event');
+    assert_equals(pc.iceGatheringState, 'new');
 
     pc.addEventListener('icegatheringstatechange', onIceGatheringStateChange);