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by Ben Hosking.
Original Post: Debugging code - the hard way
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I have spent the whole day debugging, it makes value unit tests (junit) even more than usual.
Debugging is such a difficult job when you can only test the code through the front end and checking the extra logging you have put in. The main problem I have with the code I was debugging was that it was using a struts action and almost all of the code was in the main method in the action. This basically meant it was practically impossible to test the code without using the front end and clicking and then reading the log files.
I have done a bit of refactoring but because it took me soooooo long to actually find where the problem was and then why it was going wrong, I am only doing a bit and to be honest it works and it's an action, which is pretty much self contained so it's not that much benefit refactoring it.
Today was a classic case of "everytime you fix a bug you are in danger of adding another bug" which I blogged about earlier blog entry The bug I am fixing today wasn't in the release a couple of releases ago. We found this out by my idea of setting up a running copy of the last few releases so we can easy test the code the different customers are seeing. Anyway the code works fine there so this at least gave me some clue where to start the search on what might be causing the bug. The code was actually a result of someone fixing another bug.
The bug was also quite sneaky because it was a base class that was changed the bug has filtered up which meant it was very tricky to find.
I find bug fixing can be quite boring and frustrating, especially when you are doing it like I was today by using logging messages. I must have wasted loads of time adding comments, recompiling the servlet and stopping/starting Tomcat and then running the program.
The plus side of debugging is that you do get to know the code in detail and sometimes it's quite nice not having to write to much code. Although I do get the feeling of restlessness and like I haven't really done much that day.
The best reason I heard why you should write unit tests is
"you know how long it will take to write a unit test, how long does debugging take"
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