Zod v4 best practices, patterns, and API guidance for schema validation, parsing, error handling, and type inference in TypeScript applications. Covers safeParse, object composition, refinements, transforms, codecs, branded types, v3→v4 migration, and testing schemas with Jest or Vitest. Baseline: zod ^4.3.0. Triggers…
Jest best practices, patterns, and API guidance for JavaScript/TypeScript testing. Covers mock design, async testing, matchers, timer mocks, snapshots, module mocking, configuration, and CI optimization. Baseline: jest ^30.0.0. Triggers on: jest imports, describe, it, test, expect, jest.fn, jest.mock, jest.spyOn…
Redux-Saga best practices, patterns, and API guidance for building, testing, and debugging generator-based side-effect middleware in Redux applications. Covers effect creators, fork model, channels, testing with redux-saga-test-plan, concurrency, cancellation, and modern Redux Toolkit integration. Baseline: redux-saga…
Testing patterns for Zod schemas using Jest and Vitest. Covers schema correctness testing, mock data generation, error assertion patterns, integration testing with API handlers and forms, snapshot testing with z.toJSONSchema(), and property-based testing. Baseline: zod ^4.0.0. Triggers on: test files for Zod schemas…
Write tests for Redux Sagas using redux-saga-test-plan, runSaga, and manual generator testing. Covers expectSaga (integration), testSaga (unit), providers, partial matchers, reducer integration, error simulation, and cancellation testing. Works with Jest and Vitest. Triggers on: test files for sagas…
MSW (Mock Service Worker) v2 best practices, patterns, and API guidance for API mocking in JavaScript/TypeScript tests and development. Covers handler design, server setup, response construction, testing patterns, GraphQL, and v1-to-v2 migration. Baseline: msw ^2.15.0. Triggers on: msw imports, http.get, http.post…