Widget tests for all UI constraint components
epic-cognitive-accessibility-foundation-task-018 — Write flutter_test widget tests for all UI components in this epic: WizardProgressIndicator (step rendering, semantic labels, 5-step limit enforcement), LabelledNavigationBar (label visibility, touch targets, screen reader announcements), SingleActionScreenLayout (CTA constraint, back button, choice limit), PlainLanguageErrorDisplay (message rendering, live region), InlineContextualHelpWidget (expand/collapse, semantics), and ConfirmBeforeSubmitScreen (summary accuracy, submit flow).
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Start by creating a shared test helpers file (e.g., test/helpers/accessibility_test_helpers.dart) with utilities for pumping components with required providers and design token theme. For liveRegion semantics assertions, use SemanticsHandle via tester.ensureSemantics() before asserting. When testing touch targets, use tester.getSize(find.byType(X)) and assert width >= 48 && height >= 48 in logical pixels. For the 5-step limit on WizardProgressIndicator, test both the boundary (5 steps, valid) and the violation (6 steps, should assert/throw).
Use GoldenToolkit or simple find-based assertions — avoid screenshot goldens as they are fragile across platforms. Keep each test group in its own file mirroring the component name (e.g., test/widgets/wizard_progress_indicator_test.dart).
Testing Requirements
Widget tests only (flutter_test WidgetTester). Use pumpWidget + tester.tap/tester.pump pattern. Use find.bySemanticsLabel to assert screen-reader-facing semantics. Use find.byType to count rendered widgets.
Group tests per component using group(). Mock all BLoC dependencies with MockBloc (bloc_test). Assert Semantics tree shape with tester.getSemantics(). Run tests with flutter test — no emulator required.
Target: 100% of specified acceptance criteria covered by at least one test case.
The error message registry and help content registry both depend on bundled JSON assets loaded at startup. If asset loading fails silently (e.g. malformed JSON, missing pubspec asset declaration), the entire plain-language layer falls back to empty strings or raw error codes, breaking the accessibility guarantee app-wide.
Mitigation & Contingency
Mitigation: Implement eager validation of both assets during app initialisation with an assertion failure in debug mode and a structured error log in release mode. Add integration tests that verify asset loading in the Flutter test harness on every CI run.
Contingency: Ship a hardcoded minimum-viable fallback message set directly in Dart code so the app always has at least a safe generic message, preventing a blank or code-only error surface.
The AccessibilityDesignTokenEnforcer relies on dart_code_metrics custom lint rules. If the lint toolchain is not already configured in the project's CI pipeline, integrating a new linting plugin may cause unexpected build failures or require significant CI configuration work beyond the estimated scope.
Mitigation & Contingency
Mitigation: Audit the existing dart_code_metrics configuration in the project before starting implementation. Scope the lint rules to a separate Dart package that can be integrated incrementally, starting with the most critical rule (hard-coded colors) and adding others in subsequent iterations.
Contingency: Fall back to Flutter test-level assertions (using the cognitive-accessibility-audit utility) to catch violations in CI if the lint plugin integration is delayed, preserving enforcement coverage without blocking the epic.
WizardDraftRepository must choose between shared_preferences and Hive for local persistence. Choosing the wrong store for the data volume (e.g. shared_preferences for complex nested wizard state) can lead to serialisation bugs or performance degradation, particularly on lower-end Android devices used by some NHF members.
Mitigation & Contingency
Mitigation: Define a clean repository interface first and implement shared_preferences as the initial backend. Profile serialisation round-trip time with a realistic wizard state payload (≈10 fields) before committing to either store.
Contingency: Swap the persistence backend behind the repository interface without touching wizard UI code, which is possible precisely because the repository abstraction isolates the storage detail.
The AccessibilityDesignTokenEnforcer scope could expand significantly if a large portion of existing widgets use hard-coded values. Discovering widespread violations during this epic would force either a major refactor or a decision to exclude legacy components, potentially reducing the enforcer's coverage and value.
Mitigation & Contingency
Mitigation: Run a preliminary audit of existing widgets using a simple grep for hard-coded hex colors and raw pixel values before implementation begins. Use the results to set a realistic remediation boundary for this epic and log all out-of-scope violations as tracked tech-debt items.
Contingency: Scope the enforcer to new and modified components only (via file-path filters in dart_code_metrics config), shipping a partial but immediately valuable coverage rather than blocking the epic on full-codebase remediation.