public void ShouldRequiredAll_FailWhenInvalid ()
		{
			var target = new[] { TestEnum.A, (TestEnum) 0 };

			Action act = () => target.RequiredAll (x => x.RequiredEnum ("target"));

		    act.ShouldThrow<ArgumentOutOfRangeException> ();
		}
		public void ShouldRequiredAll_Ok ()
		{
			var target = new[] { TestEnum.A, TestEnum.B };

			target.RequiredAll (x => x.RequiredEnum ("target"));
		}