third_party/web_platform_tests/websockets/eventhandlers.html

<!DOCTYPE html>
<title>WebSocket event handlers</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="websocket.js?pipe=sub"></script>
<div id="log"></div>
<script>
function testEventHandler(name) {
  test(function() {
    var ws = new WebSocket("ws://" + __SERVER__NAME + ":" + __PORT + "/" + __PATH,
                           "echo")
    assert_equals(ws["on" + name], null);
    ws["on" + name] = function() {};
    ws["on" + name] = 2;
    assert_equals(ws["on" + name], null);
  }, "Event handler for " + name + " should have [TreatNonCallableAsNull]")
}
["open", "error", "close", "message"].forEach(testEventHandler);
</script>