feat(extensions): BroadcastChannel WPT conformance

Replaces the file-backed provider by an in-memory one because proper
file locking is a hard problem that detracts from the proof of concept.

Teach the WPT runner how to extract tests from .html files because all
the relevant tests in test_util/wpt/webmessaging/broadcastchannel are
inside basics.html and interface.html.

1 files changed, 27 insertions, 0 deletions

diff --git a/cli/tests/unit/broadcast_channel_test.ts b/cli/tests/unit/broadcast_channel_test.ts
new file mode 100644
index 000000000..cfa62c856
--- /dev/null
+++ b/cli/tests/unit/broadcast_channel_test.ts
@@ -0,0 +1,27 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+import { assertEquals } from "../../../test_util/std/testing/asserts.ts";
+import { deferred } from "../../../test_util/std/async/deferred.ts";
+
+Deno.test("broadcastchannel worker", async () => {
+  const intercom = new BroadcastChannel("intercom");
+  let count = 0;
+
+  const url = new URL("../workers/broadcast_channel.ts", import.meta.url);
+  const worker = new Worker(url.href, { type: "module", name: "worker" });
+  worker.onmessage = () => intercom.postMessage(++count);
+
+  const promise = deferred();
+
+  intercom.onmessage = function (e) {
+    assertEquals(count, e.data);
+    if (count < 42) {
+      intercom.postMessage(++count);
+    } else {
+      worker.terminate();
+      intercom.close();
+      promise.resolve();
+    }
+  };
+
+  await promise;
+});