Implement planned tests

[yisding]

Summary

• build out service stubs for LLM, database, price comparison, and recommendation
• add API route placeholders and minimal React components
• add scheduler and database helpers used by integration tests
• implement all test cases from TEST_CASES.md
• set up Jest for jsdom and ignore Playwright tests

Testing

• npm test --silent

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https://chatgpt.com/codex/tasks/task_e_6881952a1ec4832bb7ff1ad86f11b525

[Copilot]

Pull Request Overview

This PR implements a comprehensive test suite for the Grocer application following a test-driven development approach. The implementation includes service stubs for LLM processing, database operations, price comparison, and recommendation services, along with API route placeholders and minimal React components to support the test cases outlined in TEST_CASES.md.

• Implements all planned test cases from unit tests to end-to-end testing infrastructure
• Creates service layer stubs and database helpers to enable testing of the full application pipeline
• Sets up Jest configuration with jsdom environment for React component testing while excluding Playwright E2E tests

Reviewed Changes

Copilot reviewed 34 out of 36 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/unit/*.test.ts	Unit tests for core services including LLM processing, price comparison, database operations, and ad retrieval
tests/integration/*.test.ts	Integration tests for scheduler, full pipeline, and API routes
tests/frontend/*.test.tsx	React component and page tests using React Testing Library
tests/e2e/userFlow.test.ts	Placeholder Playwright E2E tests for user workflows
src/services/*.ts	Service layer implementations with stub functionality for LLM, database, recommendation, and price comparison
src/components/*.tsx	Minimal React components (DealCard, Filters) to support frontend testing
src/pages/DealsPage.tsx	React page component for displaying deals
src/api/*.ts	API route implementations returning mock data
testing/*.md	Documentation for test strategy and detailed test case specifications
jest.config.ts, jest.setup.ts	Jest configuration for TypeScript and jsdom environment
package.json	Dependencies for testing frameworks and React

Comments suppressed due to low confidence (7)

tests/unit/recommendation.test.ts:7

• The variable names 'S', 'A', and 'B' are cryptic and make the test harder to understand. Consider using more descriptive names like 'TestStore', 'ProductA', 'ProductB'.

      { store: 'S', product: 'A', price: 3, unit: 'each' },

src/services/priceComparison.ts:6

• The parameter name 'threshold' is ambiguous. Consider renaming it to 'minSavingsThreshold' or 'thresholdPercentage' to clarify that it represents a percentage threshold for savings.

export function isWorthBuying(local: number, online: number, threshold = 10): boolean {

tests/unit/crudCreate.test.ts:8

• The test uses single-letter names 'S' and 'P' which make the test less readable. Consider using descriptive names like 'TestStore' and 'TestProduct'.

    const deal: Deal = { store: 'S', product: 'P', price: 1, unit: 'each' };

tests/unit/crudRead.test.ts:7

• The variable name 'deal' is misleading since the test expects this to be null. Consider renaming to 'result' or 'foundDeal' to better reflect that it may not be a deal.

    const deal = await readDeal('missing');

tests/frontend/dealCard.test.tsx:8

• The store name 'A' is not descriptive. Consider using a more realistic store name like 'TestStore' or 'SuperMarket' to make the test more readable.

    const deal: Deal = { store: 'A', product: 'Milk', price: 1.5, unit: 'each' };

src/services/database.ts:5

• Functions with double underscores like '__clearDb' follow Python naming conventions rather than TypeScript/JavaScript conventions. Consider renaming to 'clearTestDb' or 'resetDatabase' to be more explicit about its testing purpose.

export function __clearDb() {

src/services/database.ts:11

• Functions with double underscores like '__getDb' follow Python naming conventions rather than TypeScript/JavaScript conventions. Consider renaming to 'getTestDb' or 'getDatabaseState' to be more explicit about its testing purpose.

export function __getDb() {