Add test coverage of clicking close button to dismiss

osu.Game.Tests/Visual/UserInterface/TestSceneNotificationOverlay.cs

@@ -47,6 +47,35 @@ namespace osu.Game.Tests.Visual.UserInterface
             notificationOverlay.UnreadCount.ValueChanged += count => { displayedCount.Text = $"displayed count: {count.NewValue}"; };
         });
 
+        [Test]
+        public void TestDismissWithoutActivationCloseButton()
+        {
+            bool activated = false;
+            SimpleNotification notification = null!;
+
+            AddStep("post", () =>
+            {
+                activated = false;
+                notificationOverlay.Post(notification = new SimpleNotification
+                {
+                    Text = @"Welcome to osu!. Enjoy your stay!",
+                    Activated = () => activated = true,
+                });
+            });
+
+            AddStep("click to activate", () =>
+            {
+                InputManager.MoveMouseTo(notificationOverlay
+                                         .ChildrenOfType<Notification>().Single()
+                                         .ChildrenOfType<Notification.CloseButton>().Single());
+                InputManager.Click(MouseButton.Left);
+            });
+
+            AddUntilStep("wait for closed", () => notification.WasClosed);
+            AddAssert("was not activated", () => !activated);
+            AddStep("reset mouse position", () => InputManager.MoveMouseTo(Vector2.Zero));
+        }
+
         [Test]
         public void TestDismissWithoutActivationRightClick()
         {

osu.Game/Overlays/Notifications/Notification.cs

@@ -218,7 +218,7 @@ namespace osu.Game.Overlays.Notifications
             Expire();
         }
 
-        private class CloseButton : OsuClickableContainer
+        internal class CloseButton : OsuClickableContainer
         {
             private SpriteIcon icon = null!;
             private Box background = null!;