diff --git a/testing/web-platform/tests/webrtc/RTCPeerConnection-helper-test.html b/testing/web-platform/tests/webrtc/RTCPeerConnection-helper-test.html
index 42f6652ac4c4..01bd808eee1a 100644
--- a/testing/web-platform/tests/webrtc/RTCPeerConnection-helper-test.html
+++ b/testing/web-platform/tests/webrtc/RTCPeerConnection-helper-test.html
@@ -4,6 +4,10 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="RTCPeerConnection-helper.js"></script>
+<video id="videoin">
+</video>
+<video id="videoout">
+</video>
 <script>
 'use strict';
 
@@ -18,4 +22,82 @@
   await exchangeOfferAnswer(pc1, pc2);
   await waitForState(transceiver.sender.transport, 'connected');
 }, 'Setting up a connection using helpers and defaults should work');
+
+function bandwidth(stats1, stats2) {
+  const transport1 = [...stats1.values()].filter(({type}) => type === 'transport')[0];
+  const transport2 = [...stats2.values()].filter(({type}) => type === 'transport')[0];
+  const bytes = transport2.bytesReceived - transport1.bytesReceived;
+  // Timestamps are in milliseconds.
+  // Multiply by 1000 to get bytes per second, multiply by 8 to get bits/s.
+  const bandwidth = 1000 * 8 * bytes /
+        (transport2.timestamp - transport1.timestamp);
+  return bandwidth;
+}
+
+// Returns tuple of { bandwidth, fps, x-res, y-res }
+async function measureStuff(t, pc, intervalMs) {
+  const stats1 = await pc.getStats();
+  await new Promise(r => t.step_timeout(r, intervalMs));
+  const stats2 = await pc.getStats();
+  // RTCInboundStreamStats
+  const inboundRtp1List = [...stats1.values()].filter(({type}) => type === 'inbound-rtp');
+  const inboundRtp2List = [...stats2.values()].filter(({type}) => type === 'inbound-rtp');
+  const inboundRtp1 = inboundRtp1List[0];
+  const inboundRtp2 = inboundRtp2List[0];
+  const fps = 1000 * (inboundRtp2.framesReceived - inboundRtp1.framesReceived) /
+        (inboundRtp2.timestamp - inboundRtp1.timestamp);
+  const result = {
+    bandwidth: bandwidth(stats1, stats2),
+    fps: fps,
+    width: inboundRtp2.frameWidth,
+    height: inboundRtp2.frameHeight
+  };
+  // Unbreak for debugging.
+  // con sole.log('Measure: ', performance.now(), " ", JSON.stringify(result));
+  return result;
+}
+
+// Wait for a certain condition to be true on the traffic measures
+// on the PC. Will typically be conditions on resolution, framerate
+// or bandwidth.
+async function waitForCondition(t, pc, condition, maxWait, stepName) {
+  let counter = 1;
+  let measure = await measureStuff(t, pc, 1000);
+  while (counter < maxWait && !condition(measure)) {
+    measure = await measureStuff(t, pc, 1000);
+    counter += 1;
+  }
+  assert_true(condition(measure),
+              `failure in ${stepName}, measure is ${JSON.stringify(measure)}`);
+  return condition(measure);
+}
+
+promise_test(async t => {
+  const pc1 = new RTCPeerConnection();
+  const pc2 = new RTCPeerConnection();
+  t.add_cleanup(() => pc1.close());
+  t.add_cleanup(() => pc2.close());
+  const stream = await getNoiseStream({video: true});
+  const videoInDisplay = document.getElementById('videoin');
+  videoInDisplay.srcObject = stream;
+  t.add_cleanup(() => stream.getTracks().forEach(track => track.stop()));
+  const sender = pc1.addTrack(stream.getTracks()[0]);
+  pc2.ontrack = (e) => {
+    const videoOutDisplay = document.getElementById('videoout');
+    const stream = new MediaStream([e.track]);
+    videoOutDisplay.srcObject = stream;
+  }
+  exchangeIceCandidates(pc1, pc2);
+  await exchangeOfferAnswer(pc1, pc2);
+  await waitForState(sender.transport, 'connected');
+
+  // Note - we expected 640x480 here, because that's what's generated.
+  // This works in blink_tests, but not in a browser in reasonable time.
+  assert_true(await waitForCondition(t, pc2, (measure) => {
+    return (measure.bandwidth > 40000 &&
+            measure.width >= 480 &&
+            measure.fps > 9);
+  }, 15, 'video track size - may include keyframe'));
+}, 'A test video track transmits at least 40 Kbits/sec of data at 480x360 size');
+
 </script>
diff --git a/testing/web-platform/tests/webrtc/RTCPeerConnection-helper.js b/testing/web-platform/tests/webrtc/RTCPeerConnection-helper.js
index ac435279bd24..14606c80088a 100644
--- a/testing/web-platform/tests/webrtc/RTCPeerConnection-helper.js
+++ b/testing/web-platform/tests/webrtc/RTCPeerConnection-helper.js
@@ -412,10 +412,10 @@ const trackFactories = {
       ctx.fillStyle = `rgb(${contrast%255}, ${contrast*contrast%255}, ${contrast%255})`;
       const xpos = count % (width - 20);
       const ypos = count % (height - 20);
-      ctx.fillRect(xpos, ypos, xpos + 20, ypos + 20);
+      ctx.fillRect(xpos, ypos, 20, 20);
       const xpos2 = (count + width / 2) % (width - 20);
       const ypos2 = (count + height / 2) % (height - 20);
-      ctx.fillRect(xpos2, ypos2, xpos2 + 20, ypos2 + 20);
+      ctx.fillRect(xpos2, ypos2, 20, 20);
       // If signal is set (0-255), add a constant-color box of that luminance to
       // the video frame at coordinates 20 to 60 in both X and Y direction.
       // (big enough to avoid color bleed from surrounding video in some codecs,