Bug 1566312 - Add a wpt checking that microtask checkpoints happen in between render quantum. r=karlt

Differential Revision: https://phabricator.services.mozilla.com/D61728 --HG-- extra : moz-landing-system : lando
2020-02-10 08:53:29 +00:00 · 2020-02-10 08:53:29 +00:00 · b41ba52970
--- a/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-promises.https.html
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-promises.https.html
@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>
+      Test micro task checkpoints in AudioWorkletGlobalScope
+    </title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+    <script src="/webaudio/resources/audit.js"></script>
+    <meta charset=utf-8>
+  </head>
+  <body>
+    <script id="layout-test-code">
+        promise_test(async () => {
+          const context = new AudioContext();
+
+          let filePath = 'processors/promise-processor.js';
+
+          await context.audioWorklet.addModule(filePath);
+          await context.suspend();
+          let node1 = new AudioWorkletNode(context, 'promise-processor');
+          let node2 = new AudioWorkletNode(context, 'promise-processor');
+
+          // Connecting to the destination is not strictly necessary in theory,
+          // but see
+          // https://bugs.chromium.org/p/chromium/issues/detail?id=1045926
+          // for why it is in practice.
+          node1.connect(node2).connect(context.destination);
+
+          await context.resume();
+
+          // The second node is the one that is going to receive the message,
+          // per spec: it is the second that will be processed, each time.
+          const e = await new Promise((resolve) => {
+            node2.port.onmessage = resolve;
+          });
+          context.close();
+          assert_true(e.data == "ok",
+                      `Microtask checkpoints are performed
+                       in between render quantum`);
+        });
+    </script>
+  </body>
+</html>
--- a/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/processors/promise-processor.js
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioworklet-interface/processors/promise-processor.js
@ -0,0 +1,40 @@
+/**
+ * @class PromiseProcessor
+ * @extends AudioWorkletProcessor
+ *
+ * This processor creates and resolves a promise in its `process` method. When
+ * the handler passed to `then()` is called, a counter that is global in the
+ * global scope is incremented. There are two copies of this
+ * AudioWorkletNode/Processor, so the counter should always be even in the
+ * process method of the AudioWorklet processing, since the Promise completion
+ * handler are resolved in between render quanta.
+ *
+ * After a few iterations of the test, one of the worklet posts back the string
+ * "ok" to the main thread, and the test is considered a success.
+ */
+var idx = 0;
+
+class PromiseProcessor extends AudioWorkletProcessor {
+  constructor(options) {
+    super(options);
+  }
+
+  process(inputs, outputs) {
+    if (idx % 2 != 0) {
+      this.port.postMessage("ko");
+      // Don't bother continuing calling process in this case, the test has
+      // already failed.
+      return false;
+    }
+    Promise.resolve().then(() => {
+      idx++;
+      if (idx == 100) {
+        this.port.postMessage("ok");
+      }
+    });
+    // Ensure process is called again.
+    return true;
+  }
+}
+
+registerProcessor('promise-processor', PromiseProcessor);