Fixing bugs

By following TDD, the number of bugs should reduce drastically; however, no process can guarantee error-free code. There will always be edge cases that were overlooked. Previously, we outlined the TDD process for implementing a new feature; now, let's look at how can we can apply the same process to fixing bugs.

In TDD, when a bug is encountered, it is treated the same way as a new feature—you'd first write a (failing) test to reproduce the bug, and then update the code until the test passes. Having the bug documented as a test case ensures the bug stays fixed in the future, preventing regression.