1 files changed, 69 insertions, 0 deletions
diff --git a/dom/animation/test/mozilla/file_disable_animations_api_autoremove.html b/dom/animation/test/mozilla/file_disable_animations_api_autoremove.html
new file mode 100644
index 0000000000..79cb508467
--- /dev/null
+++ b/dom/animation/test/mozilla/file_disable_animations_api_autoremove.html
@@ -0,0 +1,69 @@
+<!doctype html>
+<meta charset=utf-8>
+<script src="../testcommon.js"></script>
+<body>
+<script>
+'use strict';
+
+promise_test(async t => {
+  const div = addDiv(t);
+
+  const animA = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });
+  const animB = div.animate({ opacity: 1 }, { duration: 1, fill: 'forwards' });
+
+  // This should be assert_not_own_property but our local copy of testharness.js
+  // is old.
+  assert_equals(
+    animA.replaceState,
+    undefined,
+    'Should not have a replaceState member'
+  );
+
+  animA.addEventListener(
+    'remove',
+    t.step_func(() => {
+      assert_unreached('Should not fire a remove event');
+    })
+  );
+
+  // Allow a chance for the remove event to be fired
+
+  await animA.finished;
+  await waitForNextFrame();
+}, 'Remove events should not be fired if the pref is not set');
+
+promise_test(async t => {
+  const div = addDiv(t);
+  div.style.opacity = '0.1';
+
+  const animA = div.animate(
+    { opacity: 0.2 },
+    { duration: 1, fill: 'forwards' }
+  );
+  const animB = div.animate(
+    { opacity: 0.3, composite: 'add' },
+    { duration: 1, fill: 'forwards' }
+  );
+
+  await animA.finished;
+
+  assert_approx_equals(
+    parseFloat(getComputedStyle(div).opacity),
+    0.5,
+    0.0001,
+    'Covered animation should still contribute to effect stack when adding'
+  );
+
+  animB.cancel();
+
+  assert_approx_equals(
+    parseFloat(getComputedStyle(div).opacity),
+    0.2,
+    0.0001,
+    'Covered animation should still contribute to animated style when replacing'
+  );
+}, 'Covered animations should still affect style if the pref is not set');
+
+done();
+</script>
+</body>