MutationObserver: added test on special handling for inline styles
diff --git a/css/cssom/MutationObserver-style.html b/css/cssom/MutationObserver-style.html
new file mode 100644
index 0000000..673822d
--- /dev/null
+++ b/css/cssom/MutationObserver-style.html
@@ -0,0 +1,43 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Observer notifications when updating styles</title>
+<link rel="help" href="https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-setproperty">
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<body>
+<script>
+ "use strict";
+
+ promise_test(async () => {
+ let called = 0;
+ const el = document.createElement("div");
+ document.body.appendChild(el);
+ const m = new MutationObserver(() => {
+ called++;
+ });
+ m.observe(el, { attributes: true });
+ el.style.height = "100px";
+ await Promise.resolve();
+ assert_equals(called, 1, "times callback called");
+ el.style.height = "100px";
+ await Promise.resolve();
+ assert_equals(called, 1, "times callback called");
+ }, "Updating style property with the same value does not trigger an observation callback");
+
+ promise_test(async () => {
+ let called = 0;
+ const el = document.createElement("div");
+ document.body.appendChild(el);
+ const m = new MutationObserver(() => {
+ called++;
+ });
+ m.observe(el, { attributes: true });
+ el.style.cssText = "height:100px";
+ await Promise.resolve();
+ assert_equals(called, 1, "times callback called");
+ el.style.cssText = "height:100px";
+ await Promise.resolve();
+ assert_equals(called, 2, "times callback called");
+ }, "Updating cssText triggers an observation callback even if the value is the same");
+</script>
+
