mock-generator_skill

Overview

This skill generates test mocks, stubs, and fixtures across popular frameworks (Jest, Vitest, pytest, unittest, MSW, etc.). It produces ready-to-use snippets and small helper factories so you can plug mocks directly into tests and speed up test writing. The output is framework-aware and can target functions, classes, modules, APIs, databases, and React components.

How this skill works

I inspect or ask for the target to mock (function, class, API endpoint, DB client, hook), detect the testing framework and language, then emit a minimal, idiomatic mock or fixture. The skill can create simple return-value mocks, spied methods, partial module mocks, MSW handlers, pytest fixtures, Prisma/MongoDB stubs, and factory helpers. You get code that includes setup/teardown where appropriate.

When to use it

• You need a mock for a specific function or class
• Create fixtures or factory data for tests
• Mock an HTTP/GraphQL API response or WebSocket messages
• Stub database clients (Prisma, Mongo) for unit tests
• Replace child components or hooks in React tests

Best practices

• Keep mocks small and focused—mock only what the test needs
• Prefer fixtures or factories for repeated test data to avoid duplication
• Use spies for interaction assertions and simple mocks for return values
• Reset or restore mocks between tests to avoid state leakage
• Choose MSW for integration-level API mocking and jest/vi mocks for unit-level isolation

Example use cases

• Generate a Jest mock for an async fetch module and example test that asserts calls and resolved values
• Create a pytest fixture that yields a mock database client with connect/disconnect teardown
• Produce an MSW handler file for REST and GraphQL endpoints and setup server bootstrap
• Generate a type-safe Vitest/TypeScript mock factory for User objects and a sample test using vi.fn()
• Create a Prisma client mock using jest-mock-extended and an example of mocking user.create