Unit tests for repository persistence and validation
epic-expense-type-selection-core-services-task-015 — Write unit tests for ExpenseTypeRepository covering: local draft write and read round-trip, draft cleared after final submission, Supabase upsert called with correct payload structure, mutual exclusion violation exception thrown and no write executed on invalid selection, and transaction rollback on partial failure. Use mock Supabase client and fake local storage for test isolation.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
The repository must be designed for testability: inject the Supabase client and local storage adapter via constructor parameters (not singletons). If the current implementation uses static access to Supabase.instance, refactor the constructor to accept an abstract SupabaseClientInterface before writing tests. For the rollback test, use a try/catch in the test body: configure the mock to throw on upsert, call persistFinalSelection, catch the exception, then call readDraft and assert it still contains the pre-submission draft. For payload structure assertions, define an expected map literal and use expect(capturedPayload, equals(expectedPayload)) — this makes failures readable.
Organise tests as: group('saveDraft'), group('readDraft'), group('persistFinalSelection / happy path'), group('persistFinalSelection / mutual exclusion'), group('persistFinalSelection / network failure').
Testing Requirements
Unit tests using flutter_test. Create a FakeLocalStorage class implementing the storage interface with an in-memory map — do not use Hive or SharedPreferences in unit tests. Create a MockSupabaseClient using Mockito's @GenerateMocks or a manual fake that records all upsert calls and can be configured to throw on demand. Use verify(mockClient.upsert(captureAny)) to assert payload structure.
Run with: flutter test test/unit/expense_type_repository_test.dart. Aim for 100% branch coverage on the repository class.
The per-km reimbursement rate and transit zone amounts must be read from org-specific configuration stored in Supabase. If the rate configuration table or RLS policies are not yet deployed when this epic runs, the calculation service cannot be completed and integration tests will fail.
Mitigation & Contingency
Mitigation: Define a RateConfigRepository interface and inject a stub implementation with default HLF rates from day one; write the real Supabase adapter in parallel and swap via dependency injection before merge.
Contingency: If org rate config is delayed beyond this epic's window, ship with the default-rate stub and log a prominent warning; calculate with defaults and surface a 'rates not confirmed' notice in the UI preview.
If the peer mentor opens an expense claim on two devices simultaneously, the local draft and the Supabase record may diverge. The repository's last-write-wins strategy could silently overwrite a valid selection with a stale one.
Mitigation & Contingency
Mitigation: Add an updated_at timestamp to the draft record and reject saves where the server timestamp is newer than the local copy; surface a conflict resolution prompt rather than silently overwriting.
Contingency: If conflict resolution UI is out of scope, fall back to server-authoritative reads on app foreground resume and discard local draft, notifying the user that their draft was refreshed from the server.