Unit Testing UIElements

Question

Let me just start by saying that I'm new to Unit Testing and it's actually the first time I'm trying to do it.

I am developing an application where a user can add elements to a Canvas, select them, move them around and so on. On each selected element I add an Adorner. When the control is deselected the adorner is removed.

I have a method that receives a UIElement and removes the Adorner and that is the method I'm testing.

The method I'm using to remove the adorner is:

public static void ClearElementAdorners(UIElement element)
{
    IEnumerable<Adorner> a = AdornerLayer.GetAdornerLayer(element).GetAdorners(element).AsEnumerable<Adorner>();
    if (a != null)
    {
        a.ToList().ForEach((p) =>
        {
            AdornerLayer.GetAdornerLayer(element).Remove(p);
        });
    }
}

The method I'm using to test is this one.

[TestMethod]
public void ClearElementAdornersUnitTesting()
{

    Button el = new Button();
    Button el2 = new Button();
    TestingWindow t = new TestingWindow();
    t.Show();

    t.TestingCanvas.Children.Add(el);
    t.TestingCanvas.Children.Add(el2);

    AdornerLayer alayer = AdornerLayer.GetAdornerLayer(el2);
    alayer.Add(new ClassLibrary.EditModeAdornerLayer(el2));

    ClassLibrary.AdornerOperations.ClearElementAdorners(el2);
    Assert.AreEqual(el, el2);
}

What I'm doing is creating two buttons. One of them gets an adorner and the other one stays as control for the test. I remove the adorner from the element and at the end check if they are equal. I have debugged the method to remove the adorner and I know it's working. What I don't know is how to test it. The Assert.AreEqual always fails with this error.

{"Assert.AreEqual failed. Expected:<System.Windows.Controls.Button>. Actual:<System.Windows.Controls.Button>. "}

Again this may be totally wrong, but how can I run this test? If more information is needed I will gladly provide it.

Thanks

The right way of doing this is:

Adorner[] adorner = AdornerLayer.GetAdornerLayer(el2).GetAdorners(el2); 
Assert.IsNull(adorner);

Answer 1

The buttons are not the same but at the end you are testing as if they were. The first button does not have anything to do with it. Remove it and just test for the adorner layer being empty afterwards.