Mutants to the rescue: How effective are your unit tests?

We write tests to tackle bugs, verify functionality and to ease maintenance. Using code coverage as our metric we might deem ourselves safe and our tests flawless. But how can we be sure that our tests are okay? The fact that tests cover the code doesn't imply the code is working correctly. A missing assertion can be an opening for a plethora of bugs!

In this talk we will enter the world of mutation testing. By generating mutants, i.e., faulty versions of your code, we measure how tests perform in detecting bugs. We will cover mutation tools, how they work, how to get started, how to integrate it in your builds and when you should consider it.