1 files changed, 29 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/retrospective-test.js b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/retrospective-test.js
new file mode 100644
index 0000000000..bbda190f09
--- /dev/null
+++ b/testing/web-platform/tests/webaudio/the-audio-api/the-audioparam-interface/retrospective-test.js
@@ -0,0 +1,29 @@
+// Create an audio graph on an offline context that consists of a
+// constant source and two gain nodes. One of the nodes is the node te
+// be tested and the other is the reference node.  The output from the
+// test node is in channel 0 of the offline context; the reference
+// node is in channel 1.
+//
+// Returns a dictionary with the context, source node, the test node,
+// and the reference node.
+function setupRetrospectiveGraph() {
+  // Use a sample rate that is a power of two to eliminate round-off
+  // in computing the currentTime.
+  let context = new OfflineAudioContext(2, 16384, 16384);
+  let source = new ConstantSourceNode(context);
+
+  let test = new GainNode(context);
+  let reference = new GainNode(context);
+
+  source.connect(test);
+  source.connect(reference);
+
+  let merger = new ChannelMergerNode(
+      context, {numberOfInputs: context.destination.channelCount});
+  test.connect(merger, 0, 0);
+  reference.connect(merger, 0, 1);
+
+  merger.connect(context.destination);
+
+  return {context: context, source: source, test: test, reference: reference};
+}