public override void Observe()
        {
            _repo.Setup(x => x.Get(It.IsAny<Guid>())).Returns(StateMother.Published);
            _renameHandler = new RenameStateHandler(_repo.Object);

            var renameCommand = new RenameState(Guid.NewGuid(), StateMother.Published.Name, StateMother.Published.Alias);
            _renameHandler.Handle(renameCommand);
        }
 public override void Observe()
 {
     var renameCommand = new RenameState(Guid.NewGuid(), StateMother.Published.Name, StateMother.Published.Alias);
     _renameHandler = new RenameStateHandler(_repo.Object);
     _exception = Assert.Throws<ArgumentNullException>(() => _renameHandler.Handle(renameCommand));
 }