Developers doing test-driven development locally
Sub-second watch-mode TDD
Get sub-second feedback in watch mode: the rjest daemon keeps the dependency graph in memory and re-runs only the tests a save actually affects.
The problem
Jest watch mode re-pays parts of its startup and re-resolves dependencies, so the loop between saving a file and seeing a result is slower than the flow TDD wants.
How rjest helps
The daemon holds a live dependency graph and warm workers. A save triggers exactly the affected tests on already-JITed processes, closing the edit-run loop in milliseconds.
What that looks like in practice
- ▸FS watcher and dependency graph live in the daemon, always current.
- ▸Only affected tests re-run on save — no full-suite re-resolution.
- ▸Warm workers mean no per-run V8 cold start during a session.
- ▸Same jest --watch ergonomics you already know.
Try it on this workflow
See the architecture, browse more use cases, or read the guides.