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<meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1.0, user-scalable=yes">
<title>gr-jank-detector</title>

<script src="../../../bower_components/webcomponentsjs/webcomponents-lite.min.js"></script>
<script src="../../../bower_components/web-component-tester/browser.js"></script>
<link rel="import" href="../../../test/common-test-setup.html"/>

<script src="gr-jank-detector.js"></script>

<script>
  suite('gr-jank-detector tests', () => {
    let sandbox;
    let clock;
    let instance;

    const NOW_TIME = 100;

    setup(() => {
      sandbox = sinon.sandbox.create();
      clock = sinon.useFakeTimers(NOW_TIME);
      instance = GrJankDetector;
      instance._lastFrameTime = 0;
      sandbox.stub(instance, '_requestAnimationFrame');
    });

    teardown(() => {
      sandbox.restore();
    });

    test('start() installs frame callback', () => {
      sandbox.stub(instance, '_detect');
      instance._requestAnimationFrame.callsArg(0);
      instance.start();
      assert.isTrue(instance._detect.calledOnce);
    });

    test('measures fps', () => {
      instance._detect(10);
      instance._detect(30);
      assert.equal(instance.fps, 50);
    });

    test('detects jank', () => {
      let now = 10;
      instance._detect(now);
      const fastFrame = () => instance._detect(now += 20);
      const slowFrame = () => instance._detect(now += 300);
      fastFrame();
      assert.equal(instance.jank, 0);
      _.times(4, slowFrame);
      assert.equal(instance.jank, 0);
      instance._requestAnimationFrame.reset();
      slowFrame();
      assert.equal(instance.jank, 1);
      assert.isFalse(instance._requestAnimationFrame.called);
      clock.tick(1000);
      assert.isTrue(instance._requestAnimationFrame.called);
    });
  });
</script>