The following is my completion of the first 3 parts of Bill Wake's Test First Challenge, in Tcl:

Parts 4 and 5 deal with GUI interaction, and I honestly don't want to start making this a full Tcl/Tk application, unless there's serious motivation (people really want to see it) since this is a non-paying activity ...

If you'd just like to see the resulting tests and code at the end of Part 3, you can get them here:

If you'd like to discuss anything you see here, I can be reached at