System.Linq.Tests.SelectTests.SelectSelect_SourceIsIReadOnlyCollection_ReturnsExpectedValues C# (CSharp) Метод

        public void SelectSelect_SourceIsIReadOnlyCollection_ReturnsExpectedValues()
        {
            IReadOnlyCollection<int> source = new ReadOnlyCollection<int>(new List<int> { 1, 2, 3, 4, 5 });
            Func<int, int> selector = i => i + 1;

            IEnumerable<int> query = source.Select(selector).Select(selector);

            int index = 0;
            foreach (var item in query)
            {
                index++;
                var expected = selector(selector(index));
                Assert.Equal(expected, item);
            }

            Assert.Equal(source.Count, index);
        }