System.Linq.Tests.SelectTests.Select_SourceIsIList_Last C# (CSharp) Method

        public void Select_SourceIsIList_Last()
        {
            var source = new List<int> { 1, 2, 3, 4 }.AsReadOnly().Select(i => i * 2);
            Assert.Equal(8, source.Last());
            Assert.Equal(8, source.LastOrDefault());

            Assert.Equal(6, source.Take(3).Last());
            Assert.Equal(6, source.Take(3).LastOrDefault());

            var empty = new List<int>().AsReadOnly().Select(i => i * 2);
            Assert.Throws<InvalidOperationException>(() => empty.Last());
            Assert.Equal(0, empty.LastOrDefault());
            Assert.Throws<InvalidOperationException>(() => empty.Skip(1).Last());
            Assert.Equal(0, empty.Skip(1).LastOrDefault());
        }