Run Only the Playwright Tests Your Change Can Affect

With AI writing more of our code, I keep coming back to the testing discussion. Are unit tests still useful? How much confidence do they give us when an agent writes both the implementation and the tests? I still want unit tests for business rules. But I also want to open the application, add something to a cart, and complete a checkout. An end-to-end test checks whether those pieces work together, through the interface someone uses. The problem is the waiting. If I change checkout validation, do I need to run every search scenario before getting feedback? Last week I built feature-shop, a small Nuxt shop, to try a different approach: run the E2E tests for the changed feature and the features that depend on it. Feature folders give us a starting point In the shop, search, product details, cart, and checkout each have their own feature folder. The browser tests follow the same structure. app/features/ search/ product-detail/ cart/ checkout/ tests/e2e/features/ search/ product-detail/…