fter the e-Commerce SIG talk I started chatting with a fellow attendee. We talked about what was not covered by the presentation.The conversation drifted toward Test Driven Development (TDD) —and for good reason. To my mind, there are so many benefits that it’s hard to pick a single winner.
But TDD isn’t for everyone. If writing tests before writing code feels too extreme, or if you’re working with legacy code that has no tests at all, don’t let the ideal of test-first stop you from writing any unit tests. Start where you can. Something is always better than nothing.
Here are just a few of the benefits of writing unit tests:
Confidence Through a Safety Net
Unit tests give you the confidence to make changes, knowing that regressions will be caught early.
Pressure to Break Dependencies
When a module is hard to test, that’s often a clue (a code smell): it has too many dependencies. Testing encourages better separation of concerns.
Better Object-Oriented Design
Poorly designed code is hard to test. Unit tests push you toward cleaner, more modular, and more cohesive components.
External View of Your Component
Writing tests helps you see your code from the caller’s perspective—which naturally leads to more intuitive APIs and usage patterns.
Now, ramp that up with TDD—writing the test first—and you get all of the above, plus some added magic:
Focus on What, Not How
Starting with a test forces you to clarify what you’re trying to achieve, instead of diving straight into implementation details.
Discover Code That Already Works
Sometimes you write a test… and it already passes. Why? Because the system already has that behavior.
This has led me to delete large sections of legacy code that were—frankly—doing nothing useful.
(It’s both satisfying and depressing.)
Stick to What’s Needed
TDD discourages speculative code. You implement only what the test demands—not what you think might be needed someday.
The Biggest Benefit
Ultimately this may be a shift in mindset.
What About You?
What other benefits have you experienced with unit testing or TDD?
What helped you start—or what’s still holding you back?
Update:
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Related Information
- Melbourne Scrum User Group (The replacement for MXPEG)
1 comment:
I'm don't do test-driven development myself, but I love built-in tests. (Here's my article on automated unit testing.)
The amount of time saved by having a regression suite that is run every time I compile is incredible. Sure, it probably didn't save much time during the initial development, but the time saved during maintenence is huge!
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