resetHandlers()

Removes any request handlers that were added on runtime (after the initial setupServer call).

This function accepts an optional list of request handlers to override the initial handlers to re-declare the mock definition completely on runtime.

Examples

Default behavior

The .resetHandlers() function is useful as a clean up mechanism between multiple test suites that leverage runtime request handlers.

1import { rest } from 'msw'
2import { setupServer } from 'msw/node'
3
4const server = setupServer(
5  rest.get('/book/:bookId', (req, res, ctx) => {
6    return res(ctx.json({ title: 'Lord of the Rings' }))
7  }),
8)
9
10beforeAll(() => {
11  server.listen()
12})
13
14afterEach(() => {
15  server.resetHandlers()
16})
17
18afterAll(() => {
19  server.close()
20})
21
22test('adds new book review', () => {
23  server.use(
24    // Adds a runtime request handler for posting a new book review.
25    rest.post('/book/:bookId/reviews', bookReviewResolver),
26  )
27
28  // Performing a "POST /book/:bookId/reviews" request
29  // will get the mocked response from `bookReviewResolver`.
30})
31
32test('asserts another scenario', () => {
33  // Since we call `server.resetHandlers()` after each test,
34  // this test suite will know nothing about "POST /book/:bookId/reviews".
35})

Replacing initial handlers

When provided a list of request handlers, .resetHandlers() will additionally replace any initial request handlers with the explicitly provided ones.

1const server = setupServer(rest.get('/book/:bookId', bookDetailResolver))
2
3test('first test', () => {
4  // Can handle "GET /book/:bookId".
5})
6
7test('second test', () => {
8  server.resetHandlers(rest.post('/login', loginResolver))
9
10  // This, and any subsequent tests, will NOT handle
11  // "GET /book/:bookId", because it's been reset.
12  // Only the "POST /login" request handler exists now.
13})

Be mindful when using .resetHandlers() with explicit next request handlers. It's important so that your tests remain deterministic and predictable.