5000 lines - that's a real program. Unix as described in Lions is about 10k. 10k is also reckoned to be the comprehension limit - you can't hold a whole picture of systems bigger than that

Large volumes - 10s of Mb in and out

Slightly extreme example this - almost no Java

It's a program, it does program-y things. It would have been so much easier if we'd had some testing tools.

But what does it mean to test a stylesheet?