1 files changed, 61 insertions, 0 deletions
diff --git a/testing/web-platform/tests/animation-worklet/common.js b/testing/web-platform/tests/animation-worklet/common.js
new file mode 100644
index 0000000000..ceb430b718
--- /dev/null
+++ b/testing/web-platform/tests/animation-worklet/common.js
@@ -0,0 +1,61 @@
+'use strict';
+
+function registerPassthroughAnimator() {
+  return runInAnimationWorklet(`
+    registerAnimator('passthrough', class {
+      animate(currentTime, effect) {
+        effect.localTime = currentTime;
+      }
+    });
+  `);
+}
+
+function registerConstantLocalTimeAnimator(localTime) {
+  return runInAnimationWorklet(`
+    registerAnimator('constant_time', class {
+      animate(currentTime, effect) { effect.localTime = ${localTime}; }
+    });
+  `);
+}
+
+function runInAnimationWorklet(code) {
+  return CSS.animationWorklet.addModule(
+    URL.createObjectURL(new Blob([code], {type: 'text/javascript'}))
+  );
+}
+
+function approxEquals(actual, expected){
+  // precision in ms
+  const epsilon = 0.005;
+  const lowerBound = (expected - epsilon) < actual;
+  const upperBound = (expected + epsilon) > actual;
+  return lowerBound && upperBound;
+}
+
+function waitForAsyncAnimationFrames(count) {
+  // In Chrome, waiting for N+1 main thread frames guarantees that compositor has produced
+  // at least N frames.
+  // TODO(majidvp): re-evaluate this choice once other browsers have implemented
+  // AnimationWorklet.
+  return waitForAnimationFrames(count + 1);
+}
+
+async function waitForAnimationFrameWithCondition(condition) {
+  do {
+    await new Promise(window.requestAnimationFrame);
+  } while (!condition())
+}
+
+async function waitForDocumentTimelineAdvance() {
+  const timeAtStart = document.timeline.currentTime;
+  do {
+    await new Promise(window.requestAnimationFrame);
+  } while (timeAtStart === document.timeline.currentTime)
+}
+
+// Wait until animation's effect has a non-null localTime.
+async function waitForNotNullLocalTime(animation) {
+  await waitForAnimationFrameWithCondition(_ => {
+    return animation.effect.getComputedTiming().localTime !== null;
+  });
+}
+\ No newline at end of file