1 files changed, 54 insertions, 0 deletions
diff --git a/browser/base/content/test/general/browser_tab_detach_restore.js b/browser/base/content/test/general/browser_tab_detach_restore.js
new file mode 100644
index 0000000000..d3f6a58aaa
--- /dev/null
+++ b/browser/base/content/test/general/browser_tab_detach_restore.js
@@ -0,0 +1,54 @@
+"use strict";
+
+const { TabStateFlusher } = ChromeUtils.importESModule(
+  "resource:///modules/sessionstore/TabStateFlusher.sys.mjs"
+);
+
+add_task(async function () {
+  let uri =
+    // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+    "http://example.com/browser/browser/base/content/test/general/dummy_page.html";
+
+  // Clear out the closed windows set to start
+  while (SessionStore.getClosedWindowCount() > 0) {
+    SessionStore.forgetClosedWindow(0);
+  }
+
+  let tab = BrowserTestUtils.addTab(gBrowser);
+  BrowserTestUtils.loadURIString(tab.linkedBrowser, uri);
+  await BrowserTestUtils.browserLoaded(tab.linkedBrowser, false, uri);
+  await TabStateFlusher.flush(tab.linkedBrowser);
+
+  let key = tab.linkedBrowser.permanentKey;
+  let win = gBrowser.replaceTabWithWindow(tab);
+  await new Promise(resolve => whenDelayedStartupFinished(win, resolve));
+
+  is(
+    win.gBrowser.selectedBrowser.permanentKey,
+    key,
+    "Should have properly copied the permanentKey"
+  );
+  await BrowserTestUtils.closeWindow(win);
+
+  is(
+    SessionStore.getClosedWindowCount(),
+    1,
+    "Should have restore data for the closed window"
+  );
+
+  win = SessionStore.undoCloseWindow(0);
+  await BrowserTestUtils.waitForEvent(win, "load");
+  await BrowserTestUtils.waitForEvent(
+    win.gBrowser.tabContainer,
+    "SSTabRestored"
+  );
+
+  is(win.gBrowser.tabs.length, 1, "Should have restored one tab");
+  is(
+    win.gBrowser.selectedBrowser.currentURI.spec,
+    uri,
+    "Should have restored the right page"
+  );
+
+  await promiseWindowClosed(win);
+});