Ever got the message "Fatal error: Out of memory" when running your unit tests? Or do you have to wait for more than 5 minutes for all of your unit tests to complete? We're using Docker to mitigate these and other issues. In this session I will show you how we have split up a single testsuite of 10K+ tests into manageable unit modules which are executed by Docker micro instances in parallel. And with this set up we test our application on the current PHP version, but it also allows us to test against a new major PHP version the moment it is released or even is available in beta.