Assert all in A belongs to B and all in B belongs to A

Question

I'm rather proud to have produced this Linq assertion on my own:

bool assert1 = (from e in A
               select B.Contains<T>(e, new TComparer()))
               .All(x => x == true);

bool assert2 = (from e in B
               select A.Contains<T>(e, new TComparer()))
               .All(x => x == true);

Assert(assert1 && assert2);

This will check that A and B are equal by containing the same elements i.e. A ⊆ B and B ⊆ A.

Is there a prettier way of doing this?

Answer 1

how about:

Assert.IsTrue(A.SequenceEqual(B, new SomeEqualityComparer()));

following a clarification in a comment I'm adding a sorting of the sequences. Both sequences should contain a same number of elements anyway.

OrderSequence(A).SequenceEqual(OrderSequence(B), new SomeEqualityComparer());

private static IEnumerable<StudentClass> OrderSequence(IEnumerable<StudentClass> left)
{
    IComparer<StudentClass> comparer = new TComparer();
    return left.OrderBy(a => a, comparer);
}

Answer 2

I would do this:

IComparer<T> comparer = new TComparer();
bool equal = !A.Except(B, comparer).Any() && !B.Except(A, comparer).Any();

Answer 3

What library are you using for assertions? If by any chance it's NUnit, there's a CollectionAssert class with AreEquivalent() method just for this kind of thing.

Linq can be very elegant for collection transformations, but this is exact kind of task, where it takes a huge performance hit if collections are big enough. You would need a temporary Hashtable-based collection (HashSet or Dictionary) with specialized methods to do it fast.