Practice 4. Continuous Integration
An important team discipline is to continuously integrate changes together. Frequent integration helps to ensure that modules that must fit together will, and also that the product continues to work with all the changes. Many developers have the bad habit of checking out a number of files and not checking them in again until their work is done, often days or weeks later. Developers should integrate their work every day, or even better, many times per day. This gradual introduction of changes ensures that integration problems or regressions are caught early, in addition to naturally allowing multiple developers to work on the same section of the source code. Of course, in order to catch problems it is important that your team has automated tests in place to help catch integration problems as explained in Chapter 5.