Examples of testing of the DragOver part

gistfile1.cs

 [TestMethod]
public void DragOver_With_A_Block_Source_Then_Effects_Should_Be_Set()
{
    var dropInfo = new Mock<IDropInfo>();
    dropInfo.SetupGet(m => m.Data).Returns(new[] { _club1, _club2 });
    dropInfo.SetupGet(m => m.InsertIndex).Returns(3);

    _championshipBetViewModel.DragOver(dropInfo.Object);

    dropInfo.VerifySet(x => x.DropTargetAdorner = It.IsAny<Type>(), Times.Once);
    dropInfo.VerifySet(x => x.Effects = It.IsAny<DragDropEffects>(), Times.Once);
}

[TestMethod]
public void DragOver_With_A_Non_Block_Source_Then_No_Effects_Should_Be_Set()
{
    var dropInfo = new Mock<IDropInfo>(); 
    dropInfo.SetupGet(m => m.Data).Returns(new[] { _club2, _club4 });
    dropInfo.SetupGet(m => m.InsertIndex).Returns(0);

    _championshipBetViewModel.DragOver(dropInfo.Object);

    dropInfo.VerifySet(x => x.DropTargetAdorner = It.IsAny<Type>(), Times.Never);
    dropInfo.VerifySet(x => x.Effects = It.IsAny<DragDropEffects>(), Times.Never);
}