Pro's and Con's of unit testing after the fact

Question

I have a largish complex app around 27k lines. Its essentially a rule drive multithreaded processing engine, without giving too much away Its been partially tested as it\'s been

Answer 1

This is one of these difficult value judgement types of questions.

I would mostly agree with Epaga, that writing new tests as you fix bugs (perhaps with a couple of extra tests thrown in) is a good approach.

I would add two further comments:

• Doing backed-off black box testing to a unit before making large changes can be a good idea
• Consistency testing isn't unit testing, but certain types of program lend themselves to the easy generation of consistency tests. This might be one approach to making sure you don't break things.