Why TDD is the Best Way to Fix Bugs

As a software engineer, you’re often asked to fix bugs. It’s a common scenario: after releasing a major project, once it interacts with real users, bugs inevitably happen. You’ll spend the next few days fixing those issues.

I remember having an "aha moment" when I realized that Test-Driven Development (TDD) was the most efficient way to fix bugs. Before that, I always thought, "Why use TDD? It’s easier to write the code first and then add the tests later." And that’s what I do when implementing new features. I found it more efficient to skip TDD during feature development.

But when it came to fixing bugs, I follow only TDD. Here are two reasons why TDD is not only effective but elegant for bug resolution.

1. Time Efficiency

Let’s talk about time. TDD here might seem like it takes longer at first, but it’s actually more time-efficient.

When you fix a bug without TDD, you typically start by trying to replicate the issue. Maybe you click around on the frontend, or send different payloads to the backend to reproduce the problem. Once you’ve identified the bug, you fix the code and then write a unit test to ensure the bug doesn’t come back. Let’s say:

• 20 minutes to reproduce the bug

• 5 minutes to fix the code

• 5 minutes to write the test

Total: 30 minutes.

Now, let’s apply TDD to the same situation. First, you write a test to replicate the bug. You might experiment with different inputs to trigger the bug, and often this is quicker than manually simulating the issue. Let’s say you spend 20 minutes to reproduce the bug using the test. After that, you spend 5 minutes fixing the code.

So, with TDD, you spend:

• 20 minutes to reproduce the bug using the test

• 5 minutes to fix the bug

Total: 25 minutes.

That’s hypothetical 5 minutes saved. Hope it makes sense.

2. Engineering Excellence

The second reason TDD is great for bug fixing is that it ensures you always have a test for your fixes. This improves the quality of your code. When you fix a bug with TDD, you’re not just fixing the problem; you’re also adding a safety net. The next time the code runs through your continuous integration (CI) pipeline, the test will catch any recurrence of the issue.

This leads to better engineering practices. You can be more confident that the bug won’t happen again. Adopting TDD as part of your bug-fixing process will make you a more effective engineer. It’s one of those "aha moments" that gives you a new perspective on how to work. With TDD, you not only become better at fixing bugs, but you also become more confident when refactoring your code or tackling new problems.

While many people acknowledge that TDD is good for engineering excellence, few actually apply it. But once you start using TDD for bug fixes, you’ll realize it’s great. It will save you time, make you more efficient, and reduce the number of bugs over time.

Personally, I don’t use TDD for feature development - it’s more efficient for me to write the code first and add the tests later. But for bug fixes? TDD is a must I think.

Conclusion

Next time you get a bug ticket, try using TDD to fix it. I’m confident you’ll find it more efficient and reliable. As 2024 comes to a close, I hope you have fewer bugs to deal with in the new year!

If you found this post helpful, please subscribe and share it. Cheers!