test(ui): add external filtering tests for TreeView (R8)

src/ScadaLink.CentralUI/Components/Shared/TreeView.razor

@@ -104,6 +104,12 @@ else
                 ApplyInitialExpansion(_items);
             }
         }
+
+        // Clear selection if the selected key no longer exists in the current items tree
+        if (Selectable && SelectedKey != null && _items is not null && !KeyExistsInTree(_items, SelectedKey))
+        {
+            _ = SelectedKeyChanged.InvokeAsync(null);
+        }
     }
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
@@ -133,6 +139,20 @@ else
         }
     }
 
+    private bool KeyExistsInTree(IReadOnlyList<TItem> items, object key)
+    {
+        foreach (var item in items)
+        {
+            if (key.Equals(KeySelector(item)))
+                return true;
+
+            var children = ChildrenSelector(item);
+            if (children is { Count: > 0 } && KeyExistsInTree(children, key))
+                return true;
+        }
+        return false;
+    }
+
     private void ApplyInitialExpansion(IReadOnlyList<TItem> items)
     {
         foreach (var item in items)