“Why Unit Testing Is Not an Option, But a Duty”

By someone who has fixed way too many bugs that could’ve been avoided with one simple test.

Let me say this up front: if you’re not writing unit tests, you’re asking for it. Literally. You’re inviting bugs into your code like it’s a housewarming party, and then acting surprised when they trash the place.

Unit testing isn’t a luxury. It’s not a “nice-to-have.” It’s not something you “add later” (spoiler alert: you never will). Unit testing is the digital equivalent of brushing your teeth: skip it, and things are going to rot.

“But It Takes Time!”

Of course, it takes time. Everything worth doing takes time. But you know what takes way more time?

• Spending hours debugging why your application is doing weird stuff.
• Answering panicked Slack messages because “the clients are complaining.”
• Burning your evening fixing production issues instead of relaxing with Netflix.

Unit tests are your insurance policy. They cost you a little up front, but when chaos inevitably strikes—and it will—you’ll be glad you invested.

The Basics Everyone Seems to Forget

Here are a few things I’ve seen go wrong with unit testing over and over again. These aren’t rocket science, but apparently, they’re tricky enough to miss.

1. Test One Thing at a Time. A test with 100 asserts isn’t a test; it’s bad fan fiction about what your code should do. Split it up. Keep it simple.
2. Name Your Tests Clearly. test123 or testFunctionA is not a name. “Should_fail_when_input_is_negative” is a name. Write your tests like someone who hates you will have to read them later—because someone will. 3.Mock Wisely. I get it, mocks are tempting. But if your test depends entirely on mocks, you’re basically testing…nothing. Test real functionality.
3. Don’t Skip the Edges. Sure, everything works great in ideal scenarios. But what happens when someone passes in zero, a blank string, or a negative number? That’s what I want to know.

“But My Project Is Too Big!”

I hear this all the time: “We’re working on a legacy codebase with no tests; we can’t just start adding unit tests.” Let me say this:
If you think your project is too big for unit testing, that’s exactly why you need it. Start small. Test one module, one function, one tiny piece of code. The best time to start unit testing was when your project began. The second-best time is now.

What Unit Tests Do for Me

Personally, unit tests have saved my career more times than I can count. Every time I refactor a feature and my tests pass without a single failure, it feels like winning a marathon without breaking a sweat. They give confidence—not just to me, but to everyone else working on the same codebase. And trust in code is rare, believe me.

Bottom Line: Write Them. Always.

Your tests don’t have to be perfect. Start simple. Test the basics. But do something. Because the truth is this: your code can survive without unit tests. But you can’t.

And if you’re reading this thinking, “This is nonsense; I’ve never had a bug that a test could’ve caught,” then congratulations—you’re either a genius or completely unaware of how many bugs are hiding in your code.

Choose wisely.