public void EnumerationShouldWork()
 {
     Fixture.Add(0, "hello");
     Fixture.Add(0, "cat");
     Fixture.Add(0, "dog");
     Fixture.Add(1, "house");
     Fixture.Add(2, "pool");
     Fixture.Add(2, "office");
     Fixture.Select(s => s.Key).Should().Contain(new[] { 0, 1, 2 });
     Fixture.SelectMany(s => s).Should().Contain(new[] { "hello", "cat", "dog", "house", "pool", "office" });
 }