Debugging in 4 Steps

Posted: 12 Nov 2016. Last modified on 04-Jun-22.

This article will take about 1 minute to read.

Most developers start out learning a simple hello world program in their given language. As they progress, their code gets more and more complicated. With this increased complexity comes risk, that your changes will not be doing everything that you intend them to do.

If you are on a professional engineering team, there will be a couple of different lines of defense, even before you pass your changes to QA:

Code review lets us catch domain modelling bugs
Static code analysis lets us catch bad practices
Running unit tests alerts us to unintended changes (especially aournd edge cases)

When writing software, bugs are unavoidable. Once we’ve come to accept the fact that our code is buggy, we need to take steps to diagnose the problem so that we can correct it.

1. 🔍 Observe

Reproduce the bug before you start changing code
Analyze stacktraces - they know what went wrong

2. 📚 Research

Use a search engine to find answers
Talk through the code with a senior developer

3. ☢️ Exterminate

Use a debugger to see the state of a program during execution
- When the code is simple enough, you may be able to get away with inserting print statements to inspect the current state of your program, but that is not always feasible. Debugging is a more advanced method of gathering information within a program that is already running.
Find a fix which solves the original bug

4. 🔮 Futureproof

Write documentation about how you solved the bug
Write a test case that reproduces the bug