Testing
Continuous Integration and
unit tests are challenging but critical quality components of the XP method. Make sure the technical infrastructure is not overwhelmed by running unit tests, especially as the project grows. Watch for signs that developers are unproductive because they are waiting for testing to complete. There are creative ways to scale the infrastructure to deal with these issues.
Like everything else in XP, it should be done incrementally. Create the infrastructure that serves the project today, and grow it or change it when you have to, not sooner.
