ReceiptImagePicker unit and mock tests
epic-receipt-capture-and-attachment-foundation-task-010 — Write unit tests for the ReceiptImagePickerIntegration using a mock implementation of the abstract interface. Verify that pickFromGallery and pickFromCamera return the expected ReceiptImageResult model, that null is returned on user cancellation, and that the Riverpod provider resolves to the correct platform implementation. Use mockito for the image_picker dependency.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 2 - 518 tasks
Can start after Tier 1 completes
Implementation Notes
Run build_runner to generate mockito mocks: flutter pub run build_runner build --delete-conflicting-outputs. The synthetic JPEG fixture can be a minimal valid JPEG (4 bytes: FFD8FFD9) for unit tests since MIME detection is based on the XFile.mimeType field which the mock controls. For the Riverpod provider test, use ProviderContainer(overrides: [receiptImagePickerProvider.overrideWithValue(mockImpl)]) and dispose the container in tearDown. Be explicit about the difference between unit tests (this task) and integration tests (task-009's widget-level tests) in the test file header comment.
Testing Requirements
Pure unit tests using flutter_test and mockito. Generate mockito mocks for ImagePicker using @GenerateMocks([ImagePicker]) and build_runner. Test file structure: group('pickFromGallery', ...), group('pickFromCamera', ...), group('Riverpod provider', ...). For Riverpod provider tests, use ProviderContainer from riverpod and override the receiptImagePickerProvider with a mock.
Assert that ref.read(receiptImagePickerProvider) returns the mock instance. No widget pump or Flutter binding required — these are pure logic tests.
Supabase Storage RLS policies using org/user/claim path scoping may not enforce correctly if claim ownership is not present in the JWT or if path segments are constructed differently at upload vs. read time, leading to data leakage or access denial for legitimate users.
Mitigation & Contingency
Mitigation: Define and test RLS policies in isolation before wiring to app code. Write integration tests that assert cross-org and cross-user access is denied. Use service-role key only in edge functions, never in client code.
Contingency: If client-side RLS proves insufficient, route all storage reads through a Supabase Edge Function that validates ownership before generating signed URLs, adding a controlled server-side enforcement layer.
Aggressive image compression may reduce receipt legibility below the threshold required for financial auditing, causing claim rejections or compliance failures despite technically successful uploads.
Mitigation & Contingency
Mitigation: Define minimum legibility requirements with HLF finance team before implementation. Set compression targets conservatively (e.g., max 1MB, min 80% JPEG quality) and validate with sample receipt images. Provide compression statistics in verbose/debug mode.
Contingency: If post-compression quality is disputed by auditors, increase the quality floor at the cost of larger file sizes, and add a manual override allowing users to skip compression for PDFs and high-quality scans.
The Flutter image_picker package behaves differently on iOS 17+ (PHPicker) vs older Android (Intent-based), particularly for file types, permission flows, and PDF selection, which may cause platform-specific failures not caught in development.
Mitigation & Contingency
Mitigation: Test image picker integration on physical devices for both platforms early in the sprint. Pin the image_picker package version and review changelogs before updates. Write widget tests using mock file results for each platform branch.
Contingency: If PHPicker or Android Intent differences cause blocking issues, implement separate platform-specific picker delegates behind the unified interface, allowing platform-specific fixes without breaking the shared API.