1 files changed, 101 insertions, 0 deletions
diff --git a/browser/components/sessionstore/test/browser_restoreLastActionCorrectOrder.js b/browser/components/sessionstore/test/browser_restoreLastActionCorrectOrder.js
new file mode 100644
index 0000000000..967dd7d7e7
--- /dev/null
+++ b/browser/components/sessionstore/test/browser_restoreLastActionCorrectOrder.js
@@ -0,0 +1,101 @@
+"use strict";
+
+const { _LastSession, _lastClosedActions } = ChromeUtils.importESModule(
+  "resource:///modules/sessionstore/SessionStore.sys.mjs"
+);
+
+/**
+ * Tests that the _lastClosedAction list is truncated correctly
+ * by removing oldest actions in SessionStore._addClosedAction
+ */
+add_task(async function test_undo_last_action_correct_order() {
+  SpecialPowers.pushPrefEnv({
+    set: [
+      ["browser.sessionstore.max_tabs_undo", 3],
+      ["browser.sessionstore.max_windows_undo", 1],
+    ],
+  });
+
+  gBrowser.removeAllTabsBut(gBrowser.tabs[0]);
+  await TabStateFlusher.flushWindow(window);
+
+  forgetClosedTabs(window);
+
+  const state = {
+    windows: [
+      {
+        tabs: [
+          {
+            entries: [
+              {
+                title: "example.org",
+                url: "https://example.org/",
+                triggeringPrincipal_base64,
+              },
+            ],
+          },
+          {
+            entries: [
+              {
+                title: "example.com",
+                url: "https://example.com/",
+                triggeringPrincipal_base64,
+              },
+            ],
+          },
+          {
+            entries: [
+              {
+                title: "mozilla",
+                url: "https://www.mozilla.org/",
+                triggeringPrincipal_base64,
+              },
+            ],
+          },
+          {
+            entries: [
+              {
+                title: "mozilla privacy policy",
+                url: "https://www.mozilla.org/privacy",
+                triggeringPrincipal_base64,
+              },
+            ],
+          },
+        ],
+        selected: 3,
+      },
+    ],
+  };
+
+  _LastSession.setState(state);
+  SessionStore.resetLastClosedActions();
+
+  let sessionRestored = promiseSessionStoreLoads(4 /* total restored tabs */);
+  restoreLastClosedTabOrWindowOrSession();
+  await sessionRestored;
+
+  Assert.equal(window.gBrowser.tabs.length, 4, "4 tabs have been restored");
+
+  BrowserTestUtils.removeTab(window.gBrowser.tabs[3]);
+  BrowserTestUtils.removeTab(window.gBrowser.tabs[2]);
+  Assert.equal(window.gBrowser.tabs.length, 2, "Window has one open tab");
+
+  // open and close a window
+  let win2 = await BrowserTestUtils.openNewBrowserWindow();
+  Assert.equal(win2.gBrowser.tabs.length, 1, "Second window has one open tab");
+  BrowserTestUtils.startLoadingURIString(
+    win2.gBrowser.selectedBrowser,
+    "https://example.com/"
+  );
+  await BrowserTestUtils.browserLoaded(win2.gBrowser.selectedBrowser);
+  await BrowserTestUtils.closeWindow(win2);
+
+  // close one tab and reopen it
+  BrowserTestUtils.removeTab(window.gBrowser.tabs[1]);
+  Assert.equal(window.gBrowser.tabs.length, 1, "Window has one open tabs");
+  restoreLastClosedTabOrWindowOrSession();
+  Assert.equal(window.gBrowser.tabs.length, 2, "Window now has two open tabs");
+
+  await SpecialPowers.popPrefEnv();
+  gBrowser.removeAllTabsBut(gBrowser.tabs[0]);
+});