It is a fact that most of us have to deal with legacy projects in our careers. We spend much more time maintaining and making changes to existing code rather than writing new code. The problem is, The majority of legacy systems suffer from bad design because of forgotten refactoring or simply because the team did not come up with good design solutions in the past. Thus, we have to refactor the design to make it more maintainable and adaptable.

In refactoring, our goal is to improve the maintainability of code without changing the behavior. This can be somewhat risky since many legacy projects have almost no tests. A well-designed set of tests allows us to make changes and find out very quickly whether the changes had any side-effect.

In this talk, we will take a quick tour of what "Property-Based Testing" is, how it works, and how it can be used as a safety net for refactoring.