Vimock

Vimock is an open-source library designed to help developers test code that runs inside Vim and Neovim by providing a framework for mocking the editor’s scripting environment. It enables unit tests to exercise plugins, configurations, and scripts without launching an actual editor instance, making tests faster and more deterministic.

The project focuses on the Vim ecosystem, including Vimscript and Neovim’s Lua API, and offers utilities to replace or spy on common Vim functions, access to global variables, and simulation of vim.api and related runtime features. Vimock aims to be compatible across the Vim family while remaining editor-agnostic within that family, so test suites can verify behavior across versions with a consistent interface.

Core features include function stubbing, call spying and verification, and return-value or error simulation. It also provides environment simulation capabilities such as mock buffers, windows, options, and autocommands, allowing tests to reproduce typical editing scenarios. The library is designed to be lightweight and to integrate with common test runners and workflows, minimizing intrusion into the test runtime.

Usage generally involves replacing real Vim API calls with mocks during tests, recording interactions for assertions, and deliberately injecting error conditions or edge cases. This approach helps isolate plugin logic from the editor, enabling developers to validate correctness across different Vim configurations and updates.

Development and licensing: Vimock is maintained by contributors in the Vim community and released under an open-source license. Documentation typically covers installation considerations, integration with language-specific test suites, and examples of common mocking patterns, along with contribution guidelines and repository governance.