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  <head>
    <title>
      Test Constructor: IIRFilter
    </title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <script src="/webaudio/resources/audit-util.js"></script>
    <script src="/webaudio/resources/audit.js"></script>
    <script src="/webaudio/resources/audionodeoptions.js"></script>
  </head>
  <body>
    <script id="layout-test-code">
      let context;

      let audit = Audit.createTaskRunner();

      audit.define('initialize', (task, should) => {
        context = initializeContext(should);
        task.done();
      });

      audit.define('invalid constructor', (task, should) => {
        testInvalidConstructor(should, 'IIRFilterNode', context);
        task.done();
      });

      audit.define('default constructor', (task, should) => {
        let prefix = 'node0';
        let node = testDefaultConstructor(should, 'IIRFilterNode', context, {
          prefix: prefix,
          numberOfInputs: 1,
          numberOfOutputs: 1,
          channelCount: 2,
          channelCountMode: 'max',
          channelInterpretation: 'speakers',
          constructorOptions: {feedforward: [1], feedback: [1, -.9]}
        });

        task.done();
      });

      audit.define('test AudioNodeOptions', (task, should) => {
        testAudioNodeOptions(
            should, context, 'IIRFilterNode',
            {additionalOptions: {feedforward: [1, 1], feedback: [1, .5]}});
        task.done();
      });

      audit.define('constructor options', (task, should) => {
        let node;

        let options = {feedback: [1, .5]};
        should(
            () => {
              node = new IIRFilterNode(context, options);
            },
            'node = new IIRFilterNode(, ' + JSON.stringify(options) + ')')
            .throw(TypeError);

        options = {feedforward: [1, 0.5]};
        should(
            () => {
              node = new IIRFilterNode(context, options);
            },
            'node = new IIRFilterNode(c, ' + JSON.stringify(options) + ')')
            .throw(TypeError);

        task.done();
      });

      // Test functionality of constructor.  This is needed because we have no
      // way of determining if the filter coefficients were were actually set
      // appropriately.

      // TODO(rtoy): This functionality test should be moved out to a separate
      // file.
      audit.define('functionality', (task, should) => {
        let options = {feedback: [1, .5], feedforward: [1, 1]};

        // Create two-channel offline context; sample rate and length are fairly
        // arbitrary.  Channel 0 contains the test output and channel 1 contains
        // the expected output.
        let sampleRate = 48000;
        let renderLength = 0.125;
        let testContext =
            new OfflineAudioContext(2, renderLength * sampleRate, sampleRate);

        // The test node uses the constructor.  The reference node creates the
        // same filter but uses the old factory method.
        let testNode = new IIRFilterNode(testContext, options);
        let refNode = testContext.createIIRFilter(
            Float32Array.from(options.feedforward),
            Float32Array.from(options.feedback));

        let source = testContext.createOscillator();
        source.connect(testNode);
        source.connect(refNode);

        let merger = testContext.createChannelMerger(
            testContext.destination.channelCount);

        testNode.connect(merger, 0, 0);
        refNode.connect(merger, 0, 1);

        merger.connect(testContext.destination);

        source.start();
        testContext.startRendering()
            .then(function(resultBuffer) {
              let actual = resultBuffer.getChannelData(0);
              let expected = resultBuffer.getChannelData(1);

              // The output from the two channels should be exactly equal
              // because exactly the same IIR filter should have been created.
              should(actual, 'Output of filter using new IIRFilter(...)')
                  .beEqualToArray(expected);
            })
            .then(() => task.done());
      });

      audit.run();
    </script>
  </body>
</html>