public void ShouldntAddAlterationIfAddedAlready()
        {
            alterations.AddFromAssemblyOf <DummyAlteration1>();

            alterations.ShouldContain(a => a is DummyAlteration1);

            var originalCount = alterations.Count();

            alterations.Add <DummyAlteration1>();

            (alterations.Count() == originalCount).ShouldBeTrue();
        }