Clayton Lengel-Zigich

Pragmatic technology leader

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Do You Make This Common Debugging Mistake?

Mistakes developers make when debugging their software

Hi, my name is Clayton and I use ruby-debug. There, I said it. As a matter of fact, I use ruby-debug a lot, I use it too much. I’m not even solving complex problems or debugging nitty gritty internals, I’m just being lazy. Sure, ruby-debug is a really awesome tool, but we abuse the hell out of it. If you’re reading this and thinking “hey, that’s what I do” then you’re making a mistake, a mistake that’s hurting your code.

How Debuggers are Abused

Marking breakpoints and stepping through your code, evaluating each line and variable is a pretty typical practice. There are some developers who literally figuratively could not live without their debugger. I suspect this is most common in languages where IDEs are prevalent, but lets not forget about the modify-refresh-repeat paradigm in the PHP world.

Sometimes, when I come across some unexpected result or outcome, I will immediately add my debugger statement and start stepping through the code line-by-line echoing variables, assignments and conditionals to the terminal trying to track down my problem. Recently, I had a colleague scoff at the idea of not having ruby-debug for their rails project. The idea that we need this tool for day-to-day development is absurd.

Our One Step Program

When you’re testing the logic and/or output of your code with a debugger you’re making the mistake of not writing automated tests.

There are few problems that are solved via the manual and time-consuming process of a debugger that cannot be solved with an automated test. If you’re confused about the output of a calculation or method, write a quick unit test for that method. When the logic of your application doesn’t appear correct based on the input, maybe an integration test is in order to evaluate the flow of your program.

Not only do you get rid of the debugger baggage, you gain all of the other benefits that go along with testing.

BONUS: Excuse Resolution Table

If you’re getting ready to excuse your debugging behavior, check this list of resolutions first:

But excuse, I need a debugger…

Write more tests. Don’t have tests? Quit your job.