jest‑fixture is a developer‑tool library that simplifies creating and managing file‑based test fixtures for Jest (and Vitest). It provides helpers to spin up isolated temporary directories, generate files (including JSON and package.json), read/write them, and query files via glob patterns—making it easy to set up realistic filesystem states for unit tests. It’s aimed at JavaScript/TypeScript developers writing tests that involve build tools, compilers, or any code that interacts with the file system.