v2.0.0

v2.0.0 (2023-10-23)

Important

This release is a BREAKING CHANGE. Please follow the Migration guidelines to upgrade. This release took a lot of effort to make, and I expect a bit of that effort on your part while upgrading. Most of the changes are mechanical, and a simple Find/Replace All will get you a long way. For the rest of it, you will learn how to handle requests and responses using the standard JavaScript API. Thank you!

Breaking changes

• Drops support for Node.js 16. Please upgrade to Node.js 18 or later to use the global Fetch API.
• Drops support for TypeScript < 4.7.
• All browser-side exports, like setupWorker, SetupWorkerApi, etc., must be imported from msw/browser now.
• Renames the rest object to http (rest.get -> http.get).

• Response resolver call signature is no longer (req, res, ctx) => res() but instead ({ request }) => new Response().

• The following exports are removed due to no longer being needed:
  • response
  • context and related exports (defaultContext, restContext, graphqlContext).
  • compose and createResponseComposition
• res.once() is removed in favor of the { once: boolean } option on the request handler.
• Replaces the .printHandlers() method with .listHandlers().
• Removes the NetworkError class in favor of the standard Response.error().
• Moves request error handling from the worker thread to the client thread.
• Changes the call signature of the Life-cycle Events API to accept a single object argument.
• Uses crypto.randomUUID() instead of Math.random() in the worker.
• For the full list of changes and detailed instructions on how to upgrade please see the Migration guidelines.

Features

• Adopts Fetch API primitives. Represent intercepted requests and mocked responses as Request and Response instances respectively.
• Supports Node.js v18.
• Supports ReadableStream as a mocked response body.
• Supports reading the intercepted request body as FormData.
• Supports FormData as a mocked response body.
• Uses File polyfill in Node.js.
• Supports XMLHttpRequest “upload” events when responding with a mocked stream response.
• Allows mocking a network error once using the { once: true } request handler option.
• Makes the RequestHandler API public.

Bug fixes

• Fixes the issue where the request body couldn’t be properly read as FormData.
• Fixes a set of issues related to response patching when using the FormData response body.
• Fixes the issue where URLSearchParams as the request body couldn’t be read.
• Fixes the issue where a bypassed request’s referrerPolicy was reset to a different value than the original.

• Fixes the wrong order of XMLHttpRequest events and readyState changes.
• Fixes the issue when reading an XMLHttpRequest body of responseType equal to "arraybuffer" as an incorrect buffer (previously, always assumed to be a string).
• Fixes the order of XMLHttpRequest events when the request fails.
• Keeps XMLHttpRequest status equal to 0 until the request actually resolves.
• Fixes the issue when the onload event callback was called twice for XMLHttpRequest.
• Various improvements in Node.js network behavior compliance.

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