feat: `MessageChannel` and `MessagePort` (#11051)

This commit introduces support for MessageChannel and MessagePort.
MessagePorts can be transfered across other MessagePorts.

1 files changed, 33 insertions, 0 deletions

diff --git a/cli/tests/unit/message_channel_test.ts b/cli/tests/unit/message_channel_test.ts
new file mode 100644
index 000000000..0cb2671d5
--- /dev/null
+++ b/cli/tests/unit/message_channel_test.ts
@@ -0,0 +1,33 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+// NOTE: these are just sometests to test the TypeScript types. Real coverage is
+// provided by WPT.
+import {
+  assert,
+  assertEquals,
+} from "../../../test_util/std/testing/asserts.ts";
+import { deferred } from "../../../test_util/std/async/deferred.ts";
+
+Deno.test("messagechannel", async () => {
+  const mc = new MessageChannel();
+  const mc2 = new MessageChannel();
+  assert(mc.port1);
+  assert(mc.port2);
+
+  const promise = deferred();
+
+  mc.port2.onmessage = (e) => {
+    assertEquals(e.data, "hello");
+    assertEquals(e.ports.length, 1);
+    assert(e.ports[0] instanceof MessagePort);
+    e.ports[0].close();
+    promise.resolve();
+  };
+
+  mc.port1.postMessage("hello", [mc2.port1]);
+  mc.port1.close();
+
+  await promise;
+
+  mc.port2.close();
+  mc2.port2.close();
+});