public void Where_Array_ReturnsExpectedValues_Complex()
{
int[] source = new[] { 2, 1, 3, 5, 4 };
Func<int, int, bool> complexPredicate = (value, index) => { return (value == index); };
IEnumerable<int> result = source.Where(complexPredicate);
Assert.Equal(2, result.Count());
Assert.Equal(1, result.ElementAt(0));
Assert.Equal(4, result.ElementAt(1));
}