The Beyoncé Rule

Automated tests allow software to change

A key message from the Software Engineering at Google book’s section on Testing is that: automated tests allow software to change.

These tests, running on CI (Continuous Integration), unblock large infrastructure changes. They also give increased confidence to all library version upgrades.

“If a product experiences outages or other problems as a result of infrastructure changes, but the issue wasn’t surfaced by tests in our Continuous Integration (CI) system, it is not the fault of the infrastructure change.” More colloquially, this is phrased as “If you liked it, you should have put a CI test on it,” which we call “The Beyoncé Rule.” – Software Engineering at Google