NavigationViewItem: Empty tooltip no longer shown (#3430)

* Fix empty tooltip being shown even though it shouldn't.

* Add API test.

* Improve API testing.

* Update API test.

Author: Felix-Dev

dev/NavigationView/NavigationViewItem.cpp

@@ -231,10 +231,12 @@ void NavigationViewItem::UpdateNavigationViewItemToolTip()
 void NavigationViewItem::SuggestedToolTipChanged(winrt::IInspectable const& newContent)
 {
     auto potentialString = newContent.try_as<winrt::IPropertyValue>();
-    const bool stringableToolTip = (potentialString && potentialString.Type() == winrt::PropertyType::String);
+    const bool validStringableToolTip = potentialString
+        && potentialString.Type() == winrt::PropertyType::String
+        && !potentialString.GetString().empty();
 
     winrt::IInspectable newToolTipContent{ nullptr };
-    if (stringableToolTip)
+    if (validStringableToolTip)
     {
         newToolTipContent = newContent;
     }

dev/NavigationView/NavigationView_ApiTests/NavigationViewTests.cs

@@ -1091,5 +1091,113 @@ public void VerifyHierarchicalNavigationTopModeMenuItemsSourceDoesNotCrash()
                 Content.UpdateLayout();
             });
         }
+
+        [TestMethod]
+        public void VerifyNavigationViewItemToolTipCreation()
+        {
+            if (!PlatformConfiguration.IsOsVersionGreaterThanOrEqual(OSVersion.Redstone5))
+            {
+                Log.Warning("On RS4 and earlier the test needs to be modified slightly.");
+                return;
+            }
+
+            RunOnUIThread.Execute(() =>
+            {
+                var navView = new NavigationView();
+
+                // Item with null content
+                var menuItem1 = new NavigationViewItem();
+
+                // Item with empty string as content
+                var menuItem2 = new NavigationViewItem();
+                menuItem2.Content = "";
+
+                // Item with null content and custom tooltip
+                var menuItem3 = new NavigationViewItem();
+                ToolTipService.SetToolTip(menuItem3, "Custom tooltip");
+
+                // Item with non-empty string content
+                var menuItem4 = new NavigationViewItem();
+                menuItem4.Content = "Item 4";
+
+                navView.MenuItems.Add(menuItem1);
+                navView.MenuItems.Add(menuItem2);
+                navView.MenuItems.Add(menuItem3);
+                navView.MenuItems.Add(menuItem4);
+
+                // Use a pane configuration where tooltips are shown.
+                navView.PaneDisplayMode = NavigationViewPaneDisplayMode.Left;
+                navView.IsPaneOpen = false;
+
+                Content = navView;
+                navView.UpdateLayout();
+
+                Verify.AreEqual(null, ToolTipService.GetToolTip(menuItem1), "Item 1's tooltip should have been [null].");
+                Verify.AreEqual(null, ToolTipService.GetToolTip(menuItem2), "Item 2's tooltip should have been [null].");
+                Verify.AreEqual("Custom tooltip", ToolTipService.GetToolTip(menuItem3), "Item 3's tooltip should have been \"Custom tooltip\".");
+                Verify.AreEqual("Item 4", ToolTipService.GetToolTip(menuItem4), "Item 4's tooltip should have been  \"Item 4\".");
+            });
+        }
+
+        [TestMethod]
+        public void VerifyNavigationViewItemToolTipPaneDisplayMode()
+        {
+            if (!PlatformConfiguration.IsOsVersionGreaterThanOrEqual(OSVersion.Redstone5))
+            {
+                Log.Warning("On RS4 and earlier the test needs to be modified slightly.");
+                return;
+            }
+
+            RunOnUIThread.Execute(() =>
+            {
+                var navView = new NavigationView();
+
+                // Item with non-empty string content using in-built tooltip
+                var menuItem1 = new NavigationViewItem();
+                menuItem1.Content = "Item 1";
+
+                // Item with custom tooltip
+                var menuItem2 = new NavigationViewItem();
+                menuItem2.Content = "Item 2";
+                ToolTipService.SetToolTip(menuItem2, "Custom tooltip");
+
+                navView.MenuItems.Add(menuItem1);
+                navView.MenuItems.Add(menuItem2);
+
+                Content = navView;
+
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Left, false, "Item 1", "Custom tooltip");
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Left, true, null, "Custom tooltip");
+
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.LeftCompact, false, "Item 1", "Custom tooltip");
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.LeftCompact, true, null, "Custom tooltip");
+
+                // Show tooltips again
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Left, false, "Item 1", "Custom tooltip");
+
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.LeftMinimal, true, null, "Custom tooltip");
+
+                // Show tooltips again
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Left, false, "Item 1", "Custom tooltip");
+
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Top, false, null, "Custom tooltip");
+
+                // Show tooltips again
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Left, false, "Item 1", "Custom tooltip");
+
+                SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode.Top, true, null, "Custom tooltip");
+
+                void SetPaneConfigAndVerifyToolTips(NavigationViewPaneDisplayMode paneDisplayMode, bool isPaneOpen, string expectedDefaultToolTip, string expectedCustomToolTip)
+                {
+                    Log.Comment($"Verifying tooltips with PaneDisplayMode=[{paneDisplayMode}] and IsPaneOpen=[{isPaneOpen}]");
+                    navView.PaneDisplayMode = paneDisplayMode;
+                    navView.IsPaneOpen = isPaneOpen;
+                    Content.UpdateLayout();
+
+                    Verify.AreEqual(expectedDefaultToolTip, ToolTipService.GetToolTip(menuItem1), $"Item 1's tooltip should have been \"{expectedDefaultToolTip ?? "null"}\".");
+                    Verify.AreEqual(expectedCustomToolTip, ToolTipService.GetToolTip(menuItem2), $"Item 2's tooltip should have been {expectedCustomToolTip}.");
+                }
+            });
+        }
     }
 }