Scala collection tests

My company (www.bizo.com) recently sponsored an open-source hackday,
and one of my coworkers suggested writing some specs tests for the
Scala collections library. We had recently been bitten by a couple of
bugs in views+groupBy (SI-4558 and SI-4660), so this seemed like
something that both we and the rest of the Scala community might find
useful.

My code so far can be found on GitHub: https://github.com/balshor/scala-collection-test/

I'm at a point where I think that I have enough examples (Traversable
+ TraversableLike, with failures illustrating the two above bugs in
the appropriate versions of Scala, plus several unsupported methods in
views) to illustrate how I'm planning to put these specs together, and
I'd like to solicit some feedback to see what kind of changes I should
make before getting very deep into writing tests.

Any thoughts?