I take an approach that's slightly different than what I've seen here, though I guess my answer is probably that I test chunks of code.
I will create comments that describe the logic of the program first, from start to finish (This allows me to keep my code well documented). I then go in and will write the code for a block of comments, and test it. I find that it helps me remain focused on the big picture that way, and easy to pick up a project that I've begin but had to put aside for a length of time.
I'm particular about commenting code, I hate going into code that is "self documenting" and the programmer thinks it didn't need any explanation.
in reply to Programming strategy with no on-going testing