15.tex

Commit-and-run is a crime

It's late in the afternoon. The team is churning out the last pieces of the new feature set for the iteration, and you can almost feel the rhythm in the room. John is in a bit of a hurry though. He's late for a date, but he manages to finish up his code, compile, check-in and off he goes. A few minutes later, the red light turns on. The build is broken. John didn't have time to run the automated tests, so he made a commit-and-run and thereby left everybody else hanging. The situation is now changed and the rhythm is lost. Everybody now knows that if they do an update against the version control system, they will get the broken code onto their local machine as well, and since the team has a lot to integrate this afternoon to prepare for the upcoming demo, this is quite a disruption. John effectively put the team flow to a halt because now no integration can be done before someone takes the time to revert his changes.

This scenario is way too common. Commit-and-run is a crime because it kills flow. It's one of the most common ways for a developer to try to save time for himself, that ends up wasting other peoples time and it is downright disrespectful. Still, it happens everywhere. Why? Usually because it takes too long time to build the system properly or to run the tests.

This is where you, the architect, come into play. If you've put a lot of effort into creating a flexible architecture where people can perform, taught the developers agile practices like test-driven development and set up a continuous integration server, then you also want to nurture a culture where it's not alright to waste anybody else's time and flow in any way. To be able to get that, you need to make sure the system among other things has a sound architecture for automated testing, since it will change the behavior of the developers. If tests run fast, they will run them more often, which itself is a good thing, but it also means that they won't leave their colleagues with broken code. If the tests are dependent on external systems or if they need to hit the database, reengineer them so they can be run locally with mocks or stubs, or at the very least with an in-memory database, and let the build server run them in the slow way. People should not have to wait for computers, because if they have to, they will take shortcuts which often causes problems for others instead.

Invest time in making the system fast to work with. It increases flow, lessens the reasons for working in silos and in the end makes it possible to develop faster. Mock things, create simulators, lessen dependencies, divide the system in smaller modules or do whatever you have to. Just make sure there's no reason to even think about doing a commit-and-run.

By Niclas Nilsson