gh-14049: Fix restore to pinned tab from glance (gh-14048)

src/zen/spaces/ZenSpaceManager.mjs

@@ -1010,6 +1010,14 @@ class nsZenWorkspaces {
       return null;
     }
 
+    // Closing a glance tab tears down the overlay and restores selection
+    // to its parent tab. Don't run the last-tab handling here:
+    // in a pinned-only window the glance child is the only unpinned tab,
+    // so this would switch to an empty tab and clobber the restore-to-parent.
+    if (tab.hasAttribute("glance-id")) {
+      return null;
+    }
+
     let workspaceID = tab.getAttribute("zen-workspace-id");
     if (!workspaceID) {
       return null;

src/zen/tests/glance/browser.toml

@@ -20,3 +20,5 @@ support-files = [
 ["browser_glance_prev_tab.js"]
 
 ["browser_glance_select_parent.js"]
+
+["browser_issue_14049.js"]

src/zen/tests/glance/browser_issue_14049.js

@@ -0,0 +1,101 @@
+/* Any copyright is dedicated to the Public Domain.
+   https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Regression test for gh-14049: closing a Glance ("preview") opened from a
+// pinned tab in a pinned-only window used to drop the user on a blank new tab
+// instead of restoring the pinned parent. The glance child is the last unpinned
+// tab, so removing it tripped `handleTabBeforeClose`'s "last unpinned tab
+// closed" handling, which switched to an empty tab and clobbered the
+// restore-to-parent.
+
+add_setup(async function () {
+  await SpecialPowers.pushPrefEnv({
+    set: [["zen.workspaces.open-new-tab-if-last-unpinned-tab-is-closed", true]],
+  });
+  registerCleanupFunction(async () => {
+    await SpecialPowers.popPrefEnv();
+  });
+});
+
+add_task(async function test_Glance_Close_Pinned_Parent() {
+  if (!gZenWorkspaces.workspaceEnabled) {
+    ok(true, "Workspaces disabled; the regression cannot occur. Skipping.");
+    return;
+  }
+
+  // Recreate the "only pinned tabs open" state by pinning every existing tab.
+  // The glance child opened below is then guaranteed to be the sole unpinned
+  // tab, which is the precondition the regression depends on.
+  const pinnedByTest = gBrowser.visibleTabs.filter(t => !t.pinned);
+  for (const tab of pinnedByTest) {
+    gBrowser.pinTab(tab);
+  }
+  registerCleanupFunction(() => {
+    for (const tab of pinnedByTest) {
+      if (tab.pinned && !tab.closing) {
+        gBrowser.unpinTab(tab);
+      }
+    }
+  });
+
+  const parentTab = gBrowser.selectedTab;
+  ok(parentTab.pinned, "Parent tab should be pinned");
+
+  // selectEmptyTab() is a no-op while Zen's testing mode is enabled, so the
+  // regression cannot be observed through the resulting selection alone. Spy on
+  // it instead: the bug is "selectEmptyTab gets called when a glance is closed".
+  let selectEmptyTabCalled = false;
+  const originalSelectEmptyTab = gZenWorkspaces.selectEmptyTab;
+  gZenWorkspaces.selectEmptyTab = function (...args) {
+    selectEmptyTabCalled = true;
+    return originalSelectEmptyTab.apply(this, args);
+  };
+  registerCleanupFunction(() => {
+    gZenWorkspaces.selectEmptyTab = originalSelectEmptyTab;
+  });
+
+  await openGlanceOnTab(async glanceTab => {
+    ok(
+      glanceTab.hasAttribute("glance-id"),
+      "The glance tab should have a glance-id"
+    );
+    ok(!glanceTab.pinned, "The glance child should be unpinned");
+
+    // `handleTabBeforeClose` bails early without a workspace id, so make sure
+    // the glance child carries one (as it does at teardown time).
+    if (!glanceTab.getAttribute("zen-workspace-id")) {
+      glanceTab.setAttribute(
+        "zen-workspace-id",
+        gZenWorkspaces.activeWorkspace
+      );
+    }
+
+    Assert.deepEqual(
+      gBrowser.visibleTabs.filter(t => !t.pinned),
+      [glanceTab],
+      "The glance child should be the only unpinned visible tab"
+    );
+
+    // Close the glance through the real tab-removal flow, which is what runs
+    // handleTabBeforeClose and the glance teardown.
+    await BrowserTestUtils.removeTab(glanceTab);
+  }, false);
+
+  ok(
+    !selectEmptyTabCalled,
+    "Closing a glance tab must not switch to an empty tab"
+  );
+
+  await TestUtils.waitForCondition(
+    () => gBrowser.selectedTab === parentTab && parentTab.selected,
+    "The pinned parent tab should be selected after closing the glance"
+  );
+  Assert.equal(
+    gBrowser.selectedTab,
+    parentTab,
+    "The pinned parent tab should be selected after closing the glance"
+  );
+  ok(parentTab.selected, "The pinned parent tab should be visually selected");
+});