Unit and widget tests for BLoC and screen
epic-bufdir-report-period-selection-ui-integration-task-011 — Write bloc_test unit tests for all PeriodSelectionBloc event handlers covering happy path, loading states, validation failure, and cancellation of in-flight count requests. Write widget tests for RecordCountBanner (count display, live region, gap banner) and PeriodSelectionScreen (role guard redirect, confirm button state, navigation on confirmation).
Acceptance Criteria
Technical Requirements
Execution Context
Tier 8 - 48 tasks
Can start after Tier 7 completes
Handles integration between different epics or system components. Requires coordination across multiple development streams.
Implementation Notes
For the in-flight cancellation test, inject a fake record count service that uses a Completer: emit the first SelectCustomRange, do NOT complete the first request, emit a second SelectCustomRange, complete only the second, and assert only the second result state is emitted (bloc_test's `expect` list should have exactly: [LoadingState, LoadingState, RecordCountLoadedState] not two loaded states). For widget tests of PeriodSelectionScreen, use BlocProvider.value to inject a pre-configured MockBloc rather than letting the screen create its own. Use `whenListen` from bloc_test to set up mock state streams. For role-guard tests, override currentUserRoleProvider in ProviderScope: `overrides: [currentUserRoleProvider.overrideWithValue(UserRole.peerMentor)]`.
For navigation tests, use GoRouter's testing utilities or a custom NavigatorObserver that records pushed routes.
Testing Requirements
Use bloc_test's blocTest
Widget tests must wrap under MaterialApp + ProviderScope. Aim for: 6+ BLoC unit test cases, 8+ widget test cases. Run with `flutter test --coverage` and verify >90% line coverage on period_selection_bloc.dart.
The record count query is asynchronous and may take up to 1 second on a slow connection. If the BLoC does not manage loading states carefully, the UI may show a stale count or the confirm button may be briefly enabled during the loading transition, allowing premature submission.
Mitigation & Contingency
Mitigation: Define explicit BLoC states: PeriodSelectionLoading, PeriodSelectionCountLoaded, PeriodSelectionValidationError, and PeriodSelectionReady. The confirm button must only be enabled in PeriodSelectionReady. Add a debounce of 300ms on period-change events before triggering the count query to prevent excessive calls.
Contingency: If debouncing is insufficient to prevent UX degradation on slow connections, add an optimistic loading skeleton to the RecordCountBanner that clearly communicates a pending state, and keep the confirm button disabled until the count resolves.
The confirmedReportPeriodProvider Riverpod contract between this feature and the Bufdir Export feature may not be defined yet, causing integration failures when the downstream export screen attempts to read the provider.
Mitigation & Contingency
Mitigation: Define the confirmedReportPeriodProvider as a StateProvider<DateTimeRange?> in a shared providers file at the start of this epic, before any screen code is written. Communicate the provider contract to the Bufdir Export feature team so both sides align on the same provider reference.
Contingency: If the export feature consumes the period through a different mechanism (e.g., navigation arguments), add a thin adapter that writes the confirmed period to both the Riverpod provider and the navigation argument, ensuring backward compatibility.
Flutter's live region support for screen readers is inconsistent across platforms (iOS VoiceOver vs Android TalkBack), and the record count banner must be announced on every change — a pattern that has historically required platform-channel workarounds.
Mitigation & Contingency
Mitigation: Test the live region announcement on both iOS (VoiceOver) and Android (TalkBack) early in implementation using the accessibility_test harness. Reference the project's existing live-region-announcer component (664-accessibility-live-region-announcer) for a proven implementation pattern.
Contingency: If native live region support is insufficient, wrap the record count text in a Semantics widget with a programmatically updated label string, and trigger a SemanticsService.announce call on each count update as a platform-agnostic fallback.