active-processing.https.html

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This test has a WPT meta file that expects 3 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /webaudio/the-audio-api/the-channelmergernode-interface/active-processing.https.html - WPT Dashboard Interop Dashboard

<!doctype html>

<html>

  <head>

    <title>

      Test Active Processing for ChannelMergerNode

    </title>

    <script src="/resources/testharness.js"></script>

    <script src="/resources/testharnessreport.js"></script>

    <script src="/webaudio/resources/audit.js"></script>

  </head>

  <body>

    <script id="layout-test-code">

      // AudioProcessor that sends a message to its AudioWorkletNode whenver the

      // number of channels on its input changes.

      let filePath =

          '../the-audioworklet-interface/processors/active-processing.js';

      const audit = Audit.createTaskRunner();

      let context;

      audit.define('initialize', (task, should) => {

        // Create context and load the module

        context = new AudioContext();

        should(

            context.audioWorklet.addModule(filePath),

            'AudioWorklet module loading')

            .beResolved()

            .then(() => task.done());

});

      audit.define('test', (task, should) => {

        const src = new OscillatorNode(context);

        // Number of inputs for the ChannelMergerNode.  Pretty arbitrary, but

        // should not be 1.

        const numberOfInputs = 7;

        const merger =

            new ChannelMergerNode(context, {numberOfInputs: numberOfInputs});

        const testerNode =

            new AudioWorkletNode(context, 'active-processing-tester', {

              // Use as short a duration as possible to keep the test from

              // taking too much time.

              processorOptions: {testDuration: .5},

});

        // Expected number of output channels from the merger node.  We should

        // start with the number of inputs, because the source (oscillator) is

        // actively processing.  When the source stops, the number of channels

        // should change to 0.

        const expectedValues = [numberOfInputs, 0];

        let index = 0;

        testerNode.port.onmessage = event => {

          let count = event.data.channelCount;

          let finished = event.data.finished;

          // If we're finished, end testing.

          if (finished) {

            // Verify that we got the expected number of changes.

            should(index, 'Number of distinct values')

                .beEqualTo(expectedValues.length);

            task.done();

            return;

          if (index < expectedValues.length) {

            // Verify that the number of channels matches the expected number of

            // channels.

            should(count, `Test ${index}: Number of convolver output channels`)

                .beEqualTo(expectedValues[index]);

          ++index;

};

        // Create the graph and go

        src.connect(merger).connect(testerNode).connect(context.destination);

        src.start();

        // Stop the source after a short time so we can test that the channel

        // merger changes to not actively processing and thus produces a single

        // channel of silence.

        src.stop(context.currentTime + .1);

});

      audit.run();

    </script>

  </body>

</html>