public void EmptyCloneCreatesANewEmptyUniverse()
        {
            var universe = new StateHolder();
            var aPosition = new Mock<IPosition>();
            universe.SetState(aPosition.Object, new Alive());

            var newUniverse = universe.EmptyClone();

            Assert.NotSame(newUniverse, universe);
            Assert.Equal(new Dead(), newUniverse.GetState(aPosition.Object));
        }