1 files changed, 47 insertions, 0 deletions
diff --git a/testing/web-platform/tests/web-animations/interfaces/KeyframeEffect/composite.html b/testing/web-platform/tests/web-animations/interfaces/KeyframeEffect/composite.html
new file mode 100644
index 0000000000..bcca2cad24
--- /dev/null
+++ b/testing/web-platform/tests/web-animations/interfaces/KeyframeEffect/composite.html
@@ -0,0 +1,47 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>KeyframeEffect.composite</title>
+<link rel="help"
+      href="https://drafts.csswg.org/web-animations/#dom-keyframeeffect-composite">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../../testcommon.js"></script>
+<body>
+<div id="log"></div>
+<script>
+'use strict';
+
+test(t => {
+  const anim = createDiv(t).animate(null);
+  assert_equals(anim.effect.composite, 'replace',
+                'The default value should be replace');
+}, 'Default value');
+
+test(t => {
+  const anim = createDiv(t).animate(null);
+  anim.effect.composite = 'add';
+  assert_equals(anim.effect.composite, 'add',
+                'The effect composite value should be replaced');
+}, 'Change composite value');
+
+test(t => {
+  const anim = createDiv(t).animate({ left: '10px' });
+
+  anim.effect.composite = 'add';
+  const keyframes = anim.effect.getKeyframes();
+  assert_equals(keyframes[0].composite, 'auto',
+                'unspecified keyframe composite value should be auto even ' +
+                'if effect composite is set');
+}, 'Unspecified keyframe composite value when setting effect composite');
+
+test(t => {
+  const anim = createDiv(t).animate({ left: '10px', composite: 'replace' });
+
+  anim.effect.composite = 'add';
+  const keyframes = anim.effect.getKeyframes();
+  assert_equals(keyframes[0].composite, 'replace',
+                'specified keyframe composite value should not be overridden ' +
+                'by setting effect composite');
+}, 'Specified keyframe composite value when setting effect composite');
+
+</script>