public void ShouldNotEquate_Green_White()
        {
            //assign
            ICrystal whiteCrystal = new WhiteCrystal();
            ICrystal greenCrystal = new GreenCrystal();

            //act
            bool matches = greenCrystal.Matches(whiteCrystal);

            //assert
            matches.Should().BeFalse();
        }
        public void ShouldEquate_GreenCrystals()
        {
            //assign
            ICrystal crystal1 = new GreenCrystal();
            ICrystal crystal2 = new GreenCrystal();

            //act
            bool matches = crystal1.Matches(crystal2);

            //assert
            matches.Should().BeTrue();
        }
        public void ShouldNotEquate_Green_Red()
        {
            //assign
            ICrystal redCrystal   = new RedCrystal();
            ICrystal greenCrystal = new GreenCrystal();

            //act
            bool matches = greenCrystal.Matches(redCrystal);

            //assert
            matches.Should().BeFalse();
        }