<!doctype html>
<html>
  <head>
    <title>
      Test Silent Inputs to WaveShaperNode
    </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>
  </head>
  <body>
    <script id="layout-test-code">
      let audit = Audit.createTaskRunner();
      let sampleRate = 16000;

      // Identity curve for the wave shaper: the input value is mapped directly
      // to the output value.
      let identityCurve = [-1, 0, 1];
      let nonZeroCurve = [0.5, 0.5, 0.5];

      audit.define(
          {
            label: 'test-0',
            description: 'curve output is non-zero for silent inputs'
          },
          (task, should) => {
            let {context, source, shaper} =
                setupGraph(nonZeroCurve, sampleRate, sampleRate);

            source.offset.setValueAtTime(0, 0);

            context.startRendering()
                .then(audioBuffer => {
                  should(
                      audioBuffer.getChannelData(0),
                      'WaveShaper with silent inputs and curve ' +
                          JSON.stringify(shaper.curve))
                      .beConstantValueOf(0.5);
                })
                .then(() => task.done());
          });

      audit.define(
          {
            label: 'test-1',
            description: '2x curve output is non-zero for silent inputs'
          },
          (task, should) => {
            let {context, source, shaper} =
                setupGraph(nonZeroCurve, sampleRate, sampleRate);

            source.offset.setValueAtTime(0, 0);
            shaper.overSample = '2x';

            context.startRendering()
                .then(audioBuffer => {
                  should(
                      audioBuffer.getChannelData(0),
                      'WaveShaper with ' + shaper.overSample +
                          ' oversample, silent inputs, and curve ' +
                          JSON.stringify(shaper.curve))
                      .beConstantValueOf(0.5);
                })
                .then(() => task.done());
          });

      audit.define(
          {
            label: 'test-2',
            description: 'curve output is non-zero for no inputs'
          },
          (task, should) => {
            let {context, source, shaper} =
                setupGraph(nonZeroCurve, sampleRate, sampleRate);

            source.disconnect();

            context.startRendering()
                .then(audioBuffer => {
                  should(
                      audioBuffer.getChannelData(0),
                      'WaveShaper with no inputs and curve ' +
                          JSON.stringify(shaper.curve))
                      .beConstantValueOf(0.5);
                })
                .then(() => task.done());
          });

      function setupGraph(curve, testFrames, sampleRate) {
        let context = new OfflineAudioContext(1, testFrames, sampleRate);
        let source = new ConstantSourceNode(context);
        let shaper = new WaveShaperNode(context, {curve: curve});

        source.connect(shaper).connect(context.destination);

        return {context: context, source: source, shaper: shaper};
      }

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