[plt-scheme] testing modules

Ryan Culpepper wrote:

> If you're using DrScheme, you could use the graphical test boxes
> (menu > Special > Insert Test Case).
> 
> That works fine if the module language is one of the HTDP languages.

We're running in Pretty Big at this point, but from day one we've been 
asking them to not use graphical boxes of any kind, because they don't 
play well with automarking and treating their .ss files as text files 
outside a DrScheme context.

Noel, in private e-mail, points out reasons why the sort of testing 
they've been doing doesn't scale well, and since I'm introducing modules 
in the context of a general discussion on scalability, this is an 
important point to make. Perhaps I will sketch Schemeunit in a couple of 
slides but not require them to use it. On the other hand, since they're 
headed for Java, and JUnit would be useful to them, it might be worth 
having them get a little practice in Schemeunit at this point. --PR