events: port some wpt tests

PR-URL: #33621
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-eventtarget-whatwg-once.js

@@ -0,0 +1,91 @@
+// Flags: --expose-internals --no-warnings
+'use strict';
+
+const common = require('../common');
+
+const {
+  Event,
+  EventTarget,
+} = require('internal/event_target');
+
+const {
+  strictEqual,
+} = require('assert');
+
+// Manually ported from: wpt@dom/events/AddEventListenerOptions-once.html
+{
+  const document = new EventTarget();
+  let invoked_once = false;
+  let invoked_normal = false;
+  function handler_once() {
+    invoked_once = true;
+  }
+
+  function handler_normal() {
+    invoked_normal = true;
+  }
+
+  document.addEventListener('test', handler_once, { once: true });
+  document.addEventListener('test', handler_normal);
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_once, true, 'Once handler should be invoked');
+  strictEqual(invoked_normal, true, 'Normal handler should be invoked');
+
+  invoked_once = false;
+  invoked_normal = false;
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_once, false, 'Once handler shouldn\'t be invoked again');
+  strictEqual(invoked_normal, true, 'Normal handler should be invoked again');
+  document.removeEventListener('test', handler_normal);
+}
+
+
+{
+  // Manually ported from AddEventListenerOptions-once.html
+  const document = new EventTarget();
+  let invoked_count = 0;
+  function handler() {
+    invoked_count++;
+  }
+  document.addEventListener('test', handler, { once: true });
+  document.addEventListener('test', handler);
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_count, 1, 'The handler should only be added once');
+
+  invoked_count = 0;
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_count, 0, 'The handler was added as a once listener');
+
+  invoked_count = 0;
+  document.addEventListener('test', handler, { once: true });
+  document.removeEventListener('test', handler);
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_count, 0, 'The handler should have been removed');
+}
+
+{
+  // TODO(benjamingr) fix EventTarget recursion
+  common.skip('EventTarget recursion is currently broken');
+  const document = new EventTarget();
+  let invoked_count = 0;
+  function handler() {
+    invoked_count++;
+    if (invoked_count === 1)
+      document.dispatchEvent(new Event('test'));
+  }
+  document.addEventListener('test', handler, { once: true });
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_count, 1, 'Once handler should only be invoked once');
+
+  invoked_count = 0;
+  function handler2() {
+    invoked_count++;
+    if (invoked_count === 1)
+      document.addEventListener('test', handler2, { once: true });
+    if (invoked_count <= 2)
+      document.dispatchEvent(new Event('test'));
+  }
+  document.addEventListener('test', handler2, { once: true });
+  document.dispatchEvent(new Event('test'));
+  strictEqual(invoked_count, 2, 'Once handler should only be invoked once');
+}