Problem with LazyOrderBy with multiple ThenBy

[GranBurguesa]

I haven't figured out the problem exactly, but the following test fails fof me on VS2010, .net 4.0:

[Test]
public void SortFirstAscendingSecondDescendingThirdAscending()
{
    Random random = new Random(3);

    var data = new Triple[100000];
    for (int index = 0; index < data.Length; index++)
        data[index] = new Triple(random.Next(100), random.Next(100), random.Next(100));

    var sorted1 = data.OrderBy(x => x.First).ThenByDescending(x => x.Second).ThenBy(x => x.Third);
    var sorted2 = data.LazyOrderBy(x => x.First).ThenByDescending(x => x.Second).ThenBy(x => x.Third);

    CollectionAssert.AreEqual(sorted1, sorted2);
}

I think the problem is in ElementComparer.Append, though I'm not sure how it should be fixed.

[bgrainger]

You were correct: ElementComparer.Append was implemented incorrectly. If multiple ThenBy operators were chained, it would drop the initial OrderBy comparison.