1 files changed, 28 insertions, 0 deletions
diff --git a/browser/base/content/test/tabs/browser_open_newtab_start_observer_notification.js b/browser/base/content/test/tabs/browser_open_newtab_start_observer_notification.js
new file mode 100644
index 0000000000..cb9fc3c6d7
--- /dev/null
+++ b/browser/base/content/test/tabs/browser_open_newtab_start_observer_notification.js
@@ -0,0 +1,28 @@
+"use strict";
+
+add_task(async function test_browser_open_newtab_start_observer_notification() {
+  let observerFiredPromise = new Promise(resolve => {
+    function observe(subject) {
+      Services.obs.removeObserver(observe, "browser-open-newtab-start");
+      resolve(subject.wrappedJSObject);
+    }
+    Services.obs.addObserver(observe, "browser-open-newtab-start");
+  });
+
+  // We're calling BrowserOpenTab() (rather the using BrowserTestUtils
+  // because we want to be sure that it triggers the event to fire, since
+  // it's very close to where various user-actions are triggered.
+  BrowserOpenTab();
+  const newTabCreatedPromise = await observerFiredPromise;
+  const browser = await newTabCreatedPromise;
+  const tab = gBrowser.selectedTab;
+
+  ok(true, "browser-open-newtab-start observer not called");
+  Assert.deepEqual(
+    browser,
+    tab.linkedBrowser,
+    "browser-open-newtab-start notified with the created browser"
+  );
+
+  BrowserTestUtils.removeTab(tab);
+});