Integration and error path testing for all auth services
epic-bankid-vipps-login-services-task-013 — Write integration tests covering the full authentication service layer: Vipps PKCE flow with personnummer extraction, BankID session initiation through assertion validation, biometric enrollment and session resumption, JWT auto-refresh under expiry, and auth state stream transitions. Cover error paths including network failures, user cancellation, expired sessions, and invalid tokens.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 8 - 48 tasks
Can start after Tier 7 completes
Implementation Notes
Create a `TestAuthFixtures` class with reusable mock data: test JWT tokens, mock personnummer hash, mock BiometricCapability objects. Use `mocktail` (preferred over mockito for null-safety ergonomics) to stub Supabase client, local_auth, and flutter_secure_storage. Structure the test file hierarchy to mirror the service layer: `test/auth/vipps_auth_service_test.dart`, `test/auth/bankid_auth_service_test.dart`, etc. For BLoC tests, use `bloc_test`'s `blocTest()` helper with `build`, `act`, `expect` pattern.
For stream tests, use a `StreamController` to simulate auth state changes and verify downstream behavior. Critical: biometric session resumption tests must verify that the refresh token is NOT read if the biometric challenge returns false — this is a security invariant, not just a functional one. Add a CI step in the pipeline that runs `flutter test --coverage` and uploads coverage to a reporting tool.
Testing Requirements
Use flutter_test for unit/integration layer tests and bloc_test for BLoC state sequence assertions. Organize tests into test groups: (1) VippsAuthService, (2) BankIdAuthService, (3) BiometricAuthService (enrollment), (4) BiometricAuthService (session resumption), (5) AuthSessionManager (JWT lifecycle), (6) Cross-service error paths. Use `setUp`/`tearDown` to reset mock Secure Storage and mock Supabase client. For each service, cover: (a) happy path full flow, (b) network failure mid-flow, (c) user cancellation, (d) invalid/expired token, (e) concurrent call safety (no race condition on token refresh).
Use `expectLater(stream, emitsInOrder([...]))` for auth state stream assertions. Run with `flutter test --coverage` and enforce 85% minimum via CI threshold.
The PKCE OAuth flow requires the code verifier to survive an app backgrounding during the Vipps redirect, which can trigger OS memory pressure and clear in-memory state. If the verifier is lost between authorization request and callback, the token exchange fails and the user is stranded with a confusing error.
Mitigation & Contingency
Mitigation: Store the PKCE code verifier in AuthTokenStore (Flutter Secure Storage) immediately after generation, before launching the Vipps redirect. Clear it only after a successful or explicitly failed token exchange.
Contingency: If state loss occurs in production, implement a retry flow that generates a new PKCE pair and restarts the authorization URL request, with a user-visible 'Try again' prompt rather than a generic error.
Resuming a Supabase session after biometric verification requires the session token to still be valid. If the session has expired in the background (e.g., after a long device offline period), biometric success will not produce a valid session, and the user will see a confusing 'Face ID worked but still logged out' experience.
Mitigation & Contingency
Mitigation: Before presenting the biometric prompt, check session token expiry. If expired, skip biometrics and route directly to full BankID/Vipps re-authentication. Only offer biometric re-auth if the stored refresh token is still within its validity window.
Contingency: If session expiry during biometric flow occurs in production, implement a graceful transition message ('Your session has expired — please log in again') that preserves the user's last-used authentication method preference.
BankID and Vipps may return different user identifiers (personnummer, phone number, sub claim) that must be correctly linked to an existing Supabase auth user. If the linking logic has edge cases (e.g., user previously registered via email/password), duplicate Supabase accounts may be created.
Mitigation & Contingency
Mitigation: Design the identity linking logic with explicit disambiguation: check for existing users by personnummer before creating a new Supabase identity. Implement the linking via Supabase Edge Function to keep the logic server-side and auditable.
Contingency: Implement an admin-facing account merge tool in the admin portal to resolve duplicate accounts if they occur. Add a Supabase unique constraint on the personnummer field to make duplicates fail loudly rather than silently.
The Vipps nin (personnummer) scope requires explicit approval from Vipps as part of the merchant agreement. If this scope approval is not in place before the production release, the Vipps flow will succeed but return no personnummer, making the primary business value (membership data gap fill) non-functional without user-visible error.
Mitigation & Contingency
Mitigation: Apply for Vipps nin scope approval as part of the merchant onboarding process, well before Phase 2 launch. Implement the service to gracefully handle absent nin claims and show users a clear message if personnummer could not be retrieved.
Contingency: If nin scope is delayed, ship the Vipps login flow without personnummer write-back first (delivering login value immediately) and add personnummer sync as a post-approval update with no UI changes required.