Change is inevitable with any application. Requirements change as a result of a new business rule, feature enhancement, discovery and remediation of a defect, and so on. Change is especially certain when test driving an application. Luckily, through the process of TDD, your application should be easily and safely modifiable.

If a system is loosely coupled, then changes to one part of a system should, in theory, have little to no impact on the rest of the system. A comprehensive suite of unit tests should alleviate the fear of making changes.

Unfortunately, the tests are only valid for the scenarios which they define. If sufficient tests aren't written to cover certain scenarios or edge cases, then it is certainly possible that a bug could find its way into production. If the TDD approach is not taken, or worse, tests aren't written at all, then you may discover that it is quite easy for a bug to make it through all of the checks of your code review process and CI/CD build pipeline.

Take a look at the new requirements for the Speaker Meet application.