Test framework thoughts

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

I've been thinking about the best to way to implement the test framework. We 
need it for two things:

- Compile test all the supported backends
- Making sure the supported backends actually all work, via simple unit tests
- Performance testing of various components.

Some tests require setting up an environment (e.g. network interfaces, or block 
devices) before the tests can run.  

There are a few testing libraries that are easy to incorporate (e.g. oUnit or 
Kaputt), but I've been wondering if we can just use ocamlbuild to make things 
much easier.  It supports dynamic build dependencies (much as our CIEL 
framework also does), so a test can block mid-test and wait for another target 
to finish. 

An individual test could be written as a module (say Foo), with a foo.test file 
that describes any dependencies and parameters, and ocamlbuild could just run 
them in parallel.  I'm still thinking it through, but wondering if anyone else 
has any thoughts on this. 

Anil