1 files changed, 42 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webaudio/the-audio-api/processing-model/feedback-delay-time.html b/testing/web-platform/tests/webaudio/the-audio-api/processing-model/feedback-delay-time.html
new file mode 100644
index 0000000000..96c2eb0658
--- /dev/null
+++ b/testing/web-platform/tests/webaudio/the-audio-api/processing-model/feedback-delay-time.html
@@ -0,0 +1,42 @@
+<!DOCTYPE html>
+<html class="a">
+  <head>
+    <title>Feedback cycle with delay in audio node graph</title>
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+  </head>
+  <body>
+    <script>
+      function doTest() {
+        var off = new OfflineAudioContext(1, 512, 48000);
+        var b = off.createBuffer(1, 1, 48000);
+        b.getChannelData(0)[0] = 1;
+        var impulse = new AudioBufferSourceNode(off, {buffer: b});
+        impulse.start(0);
+        var delay = new DelayNode(off, {delayTime: 128 / 48000});
+        var fb = new GainNode(off);
+        impulse.connect(fb).connect(delay).connect(fb).connect(off.destination);
+        var samples;
+        return off.startRendering().then((b) => {
+          return Promise.resolve(b.getChannelData(0));
+        });
+      }
+
+      promise_test(() => {
+        return doTest().then(samples => {
+          for (var i = 0; i < samples.length; i++) {
+            if ((i % 128) != 0) {
+              assert_equals(
+                  samples[i], 0.0,
+                  'Non-silent audio found in between delayed impulses');
+            } else {
+              assert_equals(
+                  samples[i], 1.0,
+                  'Silent audio found instead of a delayed impulse');
+            }
+          }
+        });
+      }, 'Test that a DelayNode allows a feedback loop of a single rendering quantum');
+    </script>
+  </body>
+</html>