public void AdditionalTargetTest() { var target = new Mock <IAdditionlTargets>(); target.Setup(i => i.Targets()).Returns(new object[] { 3 }); var elt = new FrameworkElement(); elt.DataContext = target.Object; var targets = elt.AllSources().ToList(); Assert.Equal(3, targets.Count); Assert.Equal(3, targets.First()); }