System.Linq.Tests.JoinTests.ResultSelectorNull C# (CSharp) Method

        public void ResultSelectorNull()
        {
            CustomerRec[] outer = new []
            {
                new CustomerRec{ name = "Prakash", custID = 98022 },
                new CustomerRec{ name = "Tim", custID = 99021 },
                new CustomerRec{ name = "Robert", custID = 99022 }
            };
            AnagramRec[] inner = new []
            {
                new AnagramRec{ name = "miT", orderID = 43455, total = 10 },
                new AnagramRec{ name = "Prakash", orderID = 323232, total = 9 }
            };

            Assert.Throws<ArgumentNullException>("resultSelector", () => outer.AsQueryable().Join(inner.AsQueryable(), e => e.name, e => e.name, (Expression<Func<CustomerRec, AnagramRec, JoinRec>>)null, new AnagramEqualityComparer()));
        }