Case study

HappyFace

HappyFace is a Firebase application structured around emulator-driven local development. It uses Cloud Functions for backend logic, Firestore rules for access control, and the @firebase/rules-unit-testing harness with Jest to verify rule behavior automatically.

RoleFull-stack engineering and Firebase architecture

TimelineOngoing

FocusFirebase Functions + Testing

Cloud functionsFirestore rule designEmulator-based devRules unit testing

Firebase + functionsBackend

Jest rules unit testsTesting

Firebase emulatorsLocal dev

The brief

Challenge

Avoid the common Firebase trap of shipping rules and functions that pass manual testing but break under realistic access patterns.

Approach

What we made

Adopted emulators as the dev loop and built rules-unit-testing coverage with Jest so access behavior is verified before deploy.

Firebase emulators wire local dev across functions, Firestore, and rules.
Jest + @firebase/rules-unit-testing enforces correct security rules.
Functions package compiled and shipped as a standalone workspace.

Outcome

Results

A Firebase project with backend functions, locked-down Firestore rules, and an automated test pass on the rules.

FirebaseCloud FunctionsFirestoreJestTypeScript

Gallery

Visual snapshots

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