How do I mock a global function like fetch?

You can use `spyOn(global, 'fetch')` combined with `mockResolvedValue` to simulate network responses without making actual HTTP requests.

What is the difference between mockClear and mockReset?

`mockClear()` resets call history like arguments and counts, while `mockReset()` also clears the mock implementation back to an undefined state.

Is Bun's mocking API compatible with Jest?

Yes, Bun provides Jest-compatible mocking through the `jest` object and similar syntax for `mock()` and `spyOn()`, making it easy to migrate existing test suites.

Can I mock external Node.js modules like Axios?

Absolutely. Using `mock.module('axios', ...)` allows you to define custom implementations for external dependencies and third-party packages.

Does this skill support async mocking?

Yes, the skill includes patterns for `mockResolvedValue` and `mockRejectedValue` to handle Promises and asynchronous function testing effectively.

Bun Test Mocking

Name: Bun Test Mocking
Author: secondsky

bysecondsky

•

Security & Testing

Simplifies creating and managing mock functions, spies, and module doubles within the Bun test environment.

About

This skill equips Claude with the expertise to implement sophisticated testing patterns using Bun's native testing toolkit. It provides comprehensive guidance on creating mock functions, overriding implementations, spying on object methods, and mocking entire modules or Node.js packages. By automating the boilerplate for test doubles and assertions, it helps developers build robust test suites for Bun-based applications with Jest-compatible syntax and optimized performance.

Key Features

21 GitHub stars
Method spying with implementation overrides and automatic restoration
Advanced module mocking for internal and external dependencies
Full Jest compatibility support for seamless migration
Comprehensive mock function creation using Bun's native API
Rich assertion patterns for verifying function calls, arguments, and return values

Use Cases

Isolating components by mocking complex module dependencies
Mocking external API calls like fetch or Axios in unit tests
Verifying side effects such as console logs or database interactions

About

Key Features

21 GitHub stars
Method spying with implementation overrides and automatic restoration
Advanced module mocking for internal and external dependencies
Full Jest compatibility support for seamless migration
Comprehensive mock function creation using Bun's native API
Rich assertion patterns for verifying function calls, arguments, and return values

Use Cases

Isolating components by mocking complex module dependencies
Mocking external API calls like fetch or Axios in unit tests
Verifying side effects such as console logs or database interactions