public void TestAddMenuItem() { // Arrange ContextMenu contextMenu = new ContextMenu(); NodeContextMenuBuilder.ContextMenu = contextMenu; MenuItem menuItem1 = new MenuItem { Header = "TestItem1" }; CollectionAssert.DoesNotContain(contextMenu.Items, menuItem1); // Act NodeContextMenuBuilder.AddContextMenuItem(menuItem1); // Assert CollectionAssert.Contains(contextMenu.Items, menuItem1); }