public void GenerateNoResultsWithNoErrorsForEmptyInput()
        {
            var items        = new string[0];
            var permutations = PermutationService.GenerateFor(items).ToArray();

            permutations.Length.ShouldBe(0);
        }
        public void GeneratesPermutationsForGivenNames()
        {
            var items        = new[] { "a", "b", "c" };
            var permutations = PermutationService.GenerateFor(items).ToArray();

            permutations.Length.ShouldBe(6);
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "a", "b", "c" }));
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "b", "a", "c" }));
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "c", "a", "b" }));
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "a", "c", "b" }));
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "b", "c", "a" }));
            permutations.ShouldContain(p => p.SequenceEqual(new[] { "c", "b", "a" }));
        }