1 files changed, 85 insertions, 0 deletions
diff --git a/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js b/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js
new file mode 100644
index 0000000000..0bb27f1146
--- /dev/null
+++ b/browser/components/contextualidentity/test/browser/browser_broadcastchannel.js
@@ -0,0 +1,85 @@
+const BASE_ORIGIN = "http://example.com";
+const URI =
+  BASE_ORIGIN +
+  "/browser/browser/components/contextualidentity/test/browser/empty_file.html";
+
+// Opens `uri' in a new tab with the provided userContextId and focuses it.
+// Returns the newly opened tab and browser.
+async function openTabInUserContext(uri, userContextId) {
+  // open the tab in the correct userContextId
+  let tab = BrowserTestUtils.addTab(gBrowser, uri, { userContextId });
+
+  // select tab and make sure its browser is focused
+  gBrowser.selectedTab = tab;
+  tab.ownerGlobal.focus();
+
+  let browser = gBrowser.getBrowserForTab(tab);
+  await BrowserTestUtils.browserLoaded(browser);
+  return { tab, browser };
+}
+
+async function runTestForReceiver(receiver) {
+  let channelName = "contextualidentity-broadcastchannel";
+
+  // reflect the received message on title
+  await SpecialPowers.spawn(receiver.browser, [channelName], function (name) {
+    content.window.testPromise = new content.window.Promise(resolve => {
+      content.window.bc = new content.window.BroadcastChannel(name);
+      content.window.bc.onmessage = function (e) {
+        content.document.title += e.data;
+        resolve();
+      };
+    });
+  });
+
+  let sender1 = await openTabInUserContext(URI, 1);
+  let sender2 = await openTabInUserContext(URI, 2);
+  sender1.message = "Message from user context #1";
+  sender2.message = "Message from user context #2";
+
+  // send a message from a tab in different user context first
+  // then send a message from a tab in the same user context
+  for (let sender of [sender1, sender2]) {
+    await SpecialPowers.spawn(
+      sender.browser,
+      [{ name: channelName, message: sender.message }],
+      function (opts) {
+        let bc = new content.window.BroadcastChannel(opts.name);
+        bc.postMessage(opts.message);
+      }
+    );
+  }
+
+  // Since sender1 sends before sender2, if the title is exactly
+  // sender2's message, sender1's message must've been blocked
+  await SpecialPowers.spawn(
+    receiver.browser,
+    [sender2.message],
+    async function (message) {
+      await content.window.testPromise.then(function () {
+        is(
+          content.document.title,
+          message,
+          "should only receive messages from the same user context"
+        );
+      });
+    }
+  );
+
+  gBrowser.removeTab(sender1.tab);
+  gBrowser.removeTab(sender2.tab);
+}
+
+add_setup(async function () {
+  // make sure userContext is enabled.
+  await SpecialPowers.pushPrefEnv({
+    set: [["privacy.userContext.enabled", true]],
+  });
+});
+
+add_task(async function test() {
+  info("Checking broadcast channel with browser tab receiver");
+  let receiver = await openTabInUserContext(URI, 2);
+  await runTestForReceiver(receiver);
+  gBrowser.removeTab(receiver.tab);
+});