080 — Integration Testing {Testing}

Purpose

Validate cross-service interactions using Firebase Emulator Suite. Test Firestore security rules, Cloud Functions triggers, and Auth flows against real emulated backends — not mocks. [EXPLICIT]

Physics — 3 Immutable Laws

1. Law of Real Contracts: Integration tests use actual Firebase Emulator instances. No mocking Firestore or Auth at this layer — the emulator IS the contract. [EXPLICIT]
2. Law of Clean State: Each test file starts with a fresh emulator state. clearFirestore() and clearAuth() run in beforeEach. [EXPLICIT]
3. Law of Boundary Testing: Integration tests validate the seams — service-to-service, rule enforcement, trigger chains. Internal logic belongs in unit tests. [EXPLICIT]

Protocol

Phase 1 — Emulator Bootstrap

1. Ensure firebase.json has emulator config (see skill 087). [EXPLICIT]
2. Install @firebase/rules-unit-testing for Firestore rules tests. [EXPLICIT]
3. Create test/integration/ directory with setup file that connects to emulator ports. [EXPLICIT]
4. Script: firebase emulators:exec --only firestore,auth,functions "vitest run --config vitest.integration.config.ts". [EXPLICIT]

Phase 2 — Test Authoring

1. Firestore Rules: Test allow/deny for each collection with authenticated/unauthenticated contexts. [EXPLICIT]
2. Cloud Functions: Trigger onCreate, onUpdate, onDelete via emulator writes. Assert side effects. [EXPLICIT]
3. Auth Flows: Create test users via Auth emulator. Validate custom claims propagation. [EXPLICIT]

Phase 3 — Assertion & Reporting

1. Assert Firestore document states after function triggers complete. [EXPLICIT]
2. Validate security rule denials throw permission-denied. [EXPLICIT]
3. Export emulator coverage report: http://localhost:8080/emulator/v1/projects/{id}:ruleCoverage. [EXPLICIT]

I/O

Input	Output
Firestore security rules (firestore.rules)	Rule coverage report (HTML)
Cloud Functions source	Trigger execution logs + assertion results
Auth flow definitions	User creation/deletion verification
firebase.json emulator config	Emulator boot + test execution

Quality Gates — 5 Checks

1. 100% Firestore rule coverage — every rule path has allow AND deny test. [EXPLICIT]
2. Function triggers tested — every onCreate/onUpdate/onDelete has integration test. [EXPLICIT]
3. Auth flows verified — sign-up, sign-in, custom claims, token refresh tested. [EXPLICIT]
4. Emulator cleanup confirmed — no state leaks between test files. [EXPLICIT]
5. CI execution — firebase emulators:exec runs in pipeline with Java 11+. [EXPLICIT]

Edge Cases

• Eventual consistency: Cloud Function triggers are async — use polling or waitForExpect.
• Batch writes in rules: Test that batched writes fail atomically when one rule denies.
• Custom claims timing: Claims update requires token refresh — test with getIdTokenResult(true).
• Emulator port conflicts: Use non-default ports in CI to avoid clashes.

Self-Correction Triggers

• Firestore rule coverage below 100% → block deploy until all paths tested.
• Function trigger test missing → lint rule flags untested exports.
• Emulator fails to start → check Java version, port availability, firebase.json config.
• Test pollution detected (order-dependent failures) → enforce beforeEach cleanup.

Usage

Example invocations:

• "/integration-testing" — Run the full integration testing workflow
• "integration testing on this project" — Apply to current context

Assumptions & Limits

• Assumes access to project artifacts (code, docs, configs) [EXPLICIT]
• Requires English-language output unless otherwise specified [EXPLICIT]
• Does not replace domain expert judgment for final decisions [EXPLICIT]