public void AnimateHorizontally_WhenXEqualsXRequest_DoesNothing() { //arrange SquareView squareView = new SquareView(); double startLeftMargin = squareView.Margin.Left; SquareViewModel squareViewModel = new SquareViewModel(0, 0, 2); //act AnimationExtensions.AnimateHorizontally(squareView, squareViewModel); //assert Assert.That(squareView.Margin.Left == startLeftMargin); }