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diff --git a/testing/web-platform/tests/css/css-transitions/CSSTransition-ready.tentative.html b/testing/web-platform/tests/css/css-transitions/CSSTransition-ready.tentative.html
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+++ b/testing/web-platform/tests/css/css-transitions/CSSTransition-ready.tentative.html
@@ -0,0 +1,73 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>CSSTransition.ready</title>
+<!-- TODO: Add a more specific link for this once it is specified. -->
+<link rel="help" href="https://drafts.csswg.org/css-transitions-2/#csstransition">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="support/helper.js"></script>
+<div id="log"></div>
+<script>
+'use strict';
+
+promise_test(async t => {
+  const div = addDiv(t);
+
+  // Set up pending transition
+  div.style.transform = 'translate(0px)';
+  getComputedStyle(div).transform;
+  div.style.transition = 'transform 100s';
+  div.style.transform = 'translate(10px)';
+  getComputedStyle(div).transform;
+
+  const animation = div.getAnimations()[0];
+  assert_true(animation.pending, 'Animation is initially pending');
+  const readyPromise = animation.ready;
+
+  // Now remove transform from transition-property and flush styles
+  div.style.transitionProperty = 'none';
+  getComputedStyle(div).transitionProperty;
+
+  try {
+    await readyPromise;
+    assert_unreached('ready promise was fulfilled');
+  } catch (err) {
+    assert_equals(err.name, 'AbortError',
+                  'ready promise is rejected with AbortError');
+    assert_equals(animation.playState, 'idle',
+                  'Animation is idle after transition was canceled');
+  }
+}, 'ready promise is rejected when a transition is canceled by updating'
+   + ' transition-property');
+
+promise_test(async t => {
+  const div = addDiv(t);
+
+  // Set up pending transition
+  div.style.marginLeft = '0px';
+  getComputedStyle(div).marginLeft;
+  div.style.transition = 'margin-left 100s';
+  div.style.marginLeft = '100px';
+  getComputedStyle(div).marginLeft;
+
+  const animation = div.getAnimations()[0];
+  assert_true(animation.pending, 'Animation is initially pending');
+  const readyPromise = animation.ready;
+
+  // Update the transition to animate to something not-interpolable
+  div.style.marginLeft = 'auto';
+  getComputedStyle(div).marginLeft;
+
+  try {
+    await readyPromise;
+    assert_unreached('ready promise was fulfilled');
+  } catch (err) {
+    assert_equals(err.name, 'AbortError',
+                  'ready promise is rejected with AbortError');
+    assert_equals(animation.playState, 'idle',
+                  'Animation is idle after transition was canceled');
+  }
+}, 'ready promise is rejected when a transition is canceled by changing'
+   + ' the transition property to something not interpolable');
+
+</script>