chromium/third_party/blink/web_tests/fast/forms/radio/radio-button-no-change-event.html

<html>
<head>
<script>
if (window.testRunner) testRunner.dumpAsText();
function load() {
    document.getElementById("1").innerText = "If you see this paragraph and the one below and both agree, the test has succeeded.";
}
function oops() {
    document.getElementById("2").innerText = "If you see this, the test has FAILED.";
}
</script>
</head>
<body onload="load()">
<p>A test to make sure we don't fire an extra change event for checked radio buttons.
We have to include a test for the case where a radio button gets unchecked because another in its group is checked.
<a href="https://bugs.webkit.org/show_bug.cgi?id=6731">Bug 6731</a> has the details.</p>
<p id="1"></p>
<p id="2">If you see this paragraph and the one above and both agree, the test has succeeded.</p>
<input type="radio" name="test" value="a" onchange="oops()" checked>
<input type="radio" name="test" value="b" onchange="oops()" checked>
</body>
</html>