Write unit tests for repository layer
epic-bufdir-report-period-selection-foundation-task-007 — Write unit tests for PeriodConfigurationRepository and BufdirAggregationRepository using flutter_test and Mockito stubs for the Supabase client. Cover: successful fetch, cache hit path, network error fallback, RLS-denied response handling, and empty result sets. Achieve 90%+ line coverage on both repository classes.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Run `flutter pub add --dev mockito build_runner` if not already present. Annotate the test file with @GenerateMocks([SupabaseClient, SupabaseQueryBuilder]) and run `flutter pub run build_runner build` to generate mocks. Organise test cases into two describe-style groups: 'PeriodConfigurationRepository' and 'BufdirAggregationRepository'. For the cache hit test, pre-seed the mock local cache with data and verify that the Supabase mock's fetch method is called zero times using Mockito's verifyNever.
For the network error fallback, throw a SocketException from the mock and assert the repository returns the pre-seeded cached list. For the RLS test, throw a PostgrestException with statusCode 403 and assert the caught exception is of type PermissionException. Keep test fixtures in a separate test/fixtures/ directory as JSON files loaded with rootBundle.loadString or hardcoded maps to keep tests readable.
Testing Requirements
Unit tests only — no widget tests or integration tests in this task. Use flutter_test test groups to organise tests by repository class and scenario. Use Mockito's @GenerateMocks annotation and build_runner to generate mock classes. Structure tests using the Arrange-Act-Assert pattern with descriptive test names.
Generate a coverage report using `flutter test --coverage` and verify both repository files appear above 90% line coverage in the LCOV report. Document any untested branches (e.g. platform-specific code paths) with a comment explaining why they are excluded.
Supabase RLS policies for period preset configuration may be missing or incorrectly scoped, causing one organisation's presets to leak to another or write operations to fail silently.
Mitigation & Contingency
Mitigation: Define and review RLS policies for the bufdir_period_presets table in the migration file before any repository code is written. Include an integration test that verifies cross-organisation isolation using two distinct org credentials.
Contingency: If RLS is misconfigured in production, immediately disable the period preset fetch endpoint and fall back to hardcoded global presets until the policy is corrected and redeployed.
The activities table may lack a composite index on (organisation_id, activity_date), causing the range count query in BufdirAggregationRepository to perform a full table scan and exceed acceptable response time for large organisations.
Mitigation & Contingency
Mitigation: Add a migration that creates a composite index on (organisation_id, activity_date) as part of this epic. Benchmark the count query against a representative dataset (10 000+ rows) before marking the epic complete.
Contingency: If query latency is unacceptable after indexing, move the count query to a Supabase RPC function that leverages a materialised view or partial index, accepting a slight staleness window.
Flutter's native date picker widgets have known accessibility gaps (missing semantic labels, non-standard focus traversal) that may prevent WCAG 2.2 AA compliance out of the box, requiring a custom implementation.
Mitigation & Contingency
Mitigation: Evaluate third-party accessible date picker packages (e.g., table_calendar with custom semantics) against WCAG 2.2 AA criteria before beginning implementation. Document the chosen approach in the epic kick-off.
Contingency: If no package meets accessibility requirements, implement a simple text-field-based date entry with explicit semantic labels and format hints as an accessible fallback, deferring a fully visual calendar to a later iteration.