CollectionAssert use with generics?

You can use CollectionAssert with generic collections. The trick is to understand that the CollectionAssert methods operate on ICollection, and although few generic collection interfaces implement ICollection, List<T> does.

Thus, you can get around this limitation by using the ToList extension method:

IEnumerable<Foo> expected = //...
IEnumerable<Foo> actual = //...
CollectionAssert.AreEqual(expected.ToList(), actual.ToList());

That said, I still consider CollectionAssert broken in a lot of other ways, so I tend to use Assert.IsTrue(bool) with the LINQ extension methods, like this:

Assert.IsTrue(expected.SequenceEqual(actual));

FWIW, I’m currently using these extension methods to perform other comparisons:

public static class EnumerableExtension
{
    public static bool IsEquivalentTo(this IEnumerable first, IEnumerable second)
    {
        var secondList = second.Cast<object>().ToList();
        foreach (var item in first)
        {
            var index = secondList.FindIndex(item.Equals);
            if (index < 0)
            {
                return false;
            }
            secondList.RemoveAt(index);
        }
        return secondList.Count == 0;
    }

    public static bool IsSubsetOf(this IEnumerable first, IEnumerable second)
    {
        var secondList = second.Cast<object>().ToList();
        foreach (var item in first)
        {
            var index = secondList.FindIndex(item.Equals);
            if (index < 0)
            {
                return false;
            }
            secondList.RemoveAt(index);
        }
        return true;
    }
}