Fetch Mocking Library

fetch-mock is a comprehensive library for mocking HTTP requests made using the `fetch` API in JavaScript and TypeScript applications. It is widely used in testing environments to isolate network calls and control their responses. The current stable version is `12.6.0`, with a generally active release cadence, often seeing patch updates multiple times a month to address bug fixes and introduce minor features. Key differentiators include its extensive support for the `fetch` API specification, including advanced behaviors like streaming and aborting requests. It offers declarative matching for various aspects of an HTTP request (URL, headers, body, query parameters), provides convenient shorthands for common scenarios, supports delaying responses, and can function as a spy to observe real network activity. The library is isomorphic, working equally well in Node.js (requiring Node.js 18+ for full feature operation) and modern browser environments, and can be extended with custom matchers.