1 files changed, 78 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js b/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js
new file mode 100644
index 0000000000..f816e918a2
--- /dev/null
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/processors/zero-outputs-check-processor.js
@@ -0,0 +1,78 @@
+/**
+ * Returns true if a given AudioPort is completely filled with zero samples.
+ * "AudioPort" is a short-hand for FrozenArray<FrozenArray<Float32Array>>.
+ *
+ * @param {FrozenArray<FrozenArray<Float32Array>>} audioPort
+ * @returns bool
+ */
+function IsAllZero(audioPort) {
+  for (let busIndex = 0; busIndex < audioPort.length; ++busIndex) {
+    const audioBus = audioPort[busIndex];
+    for (let channelIndex = 0; channelIndex < audioBus.length; ++channelIndex) {
+      const audioChannel = audioBus[channelIndex];
+      for (let sample = 0; sample < audioChannel.length; ++sample) {
+        if (audioChannel[sample] != 0)
+          return false;
+      }
+    }
+  }
+  return true;
+}
+
+const kRenderQuantumFrames = 128;
+const kTestLengthInSec = 1.0;
+const kPulseDuration = 100;
+
+/**
+ * Checks the |outputs| argument of AudioWorkletProcessor.process() and
+ * send a message to an associated AudioWorkletNode. It needs to be all zero
+ * at all times.
+ *
+ * @class ZeroOutputsCheckProcessor
+ * @extends {AudioWorkletProcessor}
+ */
+class ZeroOutputsCheckProcessor extends AudioWorkletProcessor {
+  constructor() {
+    super();
+    this.startTime = currentTime;
+    this.counter = 0;
+  }
+
+  process(inputs, outputs) {
+    if (!IsAllZero(outputs)) {
+      this.port.postMessage({
+        type: 'assertion',
+        success: false,
+        message: 'Unexpected Non-zero sample found in |outputs|.'
+      });
+      return false;
+    }
+
+    if (currentTime - this.startTime >= kTestLengthInSec) {
+      this.port.postMessage({
+        type: 'assertion',
+        success: true,
+        message: `|outputs| has been all zeros for ${kTestLengthInSec} ` +
+            'seconds as expected.'
+      });
+      return false;
+    }
+
+    // Every ~0.25 second (100 render quanta), switch between outputting white
+    // noise and just exiting without doing anything. (from crbug.com/1099756)
+    this.counter++;
+    if (Math.floor(this.counter / kPulseDuration) % 2 == 0)
+      return true;
+
+    let output = outputs[0];
+    for (let channel = 0; channel < output.length; ++channel) {
+      for (let sample = 0; sample < 128; sample++) {
+        output[channel][sample] = 0.1 * (Math.random() - 0.5);
+      }
+    }
+
+    return true;
+  }
+}
+
+registerProcessor('zero-outputs-check-processor', ZeroOutputsCheckProcessor);