@mswjs/interceptors/src/utils/fetchUtils.test.ts

Low-level HTTP/HTTPS/XHR/fetch request interception library.

import { describe, it, expect } from 'vitest'
import { FetchRequest, FetchResponse } from './fetchUtils'

describe('FetchRequest', () => {
  const URL = 'https://example.com/'

  it('passes instanceof check with the regular Request', () => {
    expect(new FetchRequest(URL)).toBeInstanceOf(Request)
  })

  it('creates a request with a non-configurable method', () => {
    expect
      .soft(new FetchRequest(URL, { method: 'CONNECT' }))
      .toHaveProperty('method', 'CONNECT')

    expect
      .soft(new FetchRequest(URL, { method: 'TRACE' }))
      .toHaveProperty('method', 'TRACE')
    expect
      .soft(new FetchRequest(new FetchRequest(URL, { method: 'TRACE' })))
      .toHaveProperty('method', 'TRACE')

    expect
      .soft(new FetchRequest(URL, { method: 'TRACK' }))
      .toHaveProperty('method', 'TRACK')
    expect
      .soft(new FetchRequest(new FetchRequest(URL, { method: 'TRACK' })))
      .toHaveProperty('method', 'TRACK')
  })

  it('creates a request with a non-configurable mode', () => {
    expect
      .soft(new FetchRequest(URL, { mode: 'navigate' }))
      .toHaveProperty('mode', 'navigate')
    expect
      .soft(new FetchRequest(new FetchRequest(URL, { mode: 'navigate' })))
      .toHaveProperty('mode', 'navigate')

    expect
      .soft(new FetchRequest(URL, { mode: 'websocket' }))
      .toHaveProperty('mode', 'websocket')
    expect
      .soft(new FetchRequest(new FetchRequest(URL, { mode: 'websocket' })))
      .toHaveProperty('mode', 'websocket')

    expect
      .soft(new FetchRequest(URL, { mode: 'webtransport' }))
      .toHaveProperty('mode', 'webtransport')
    expect
      .soft(new FetchRequest(new FetchRequest(URL, { mode: 'webtransport' })))
      .toHaveProperty('mode', 'webtransport')
  })

  it('ignores body for the requests without a body', () => {
    expect
      .soft(new FetchRequest(URL, { body: null }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { body: undefined }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { body: 'hello' }))
      .toHaveProperty('body', null)

    expect
      .soft(new FetchRequest(URL, { method: 'GET', body: 'hello' }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { method: 'HEAD', body: 'hello' }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { method: 'CONNECT', body: 'hello' }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { method: 'TRACE', body: 'hello' }))
      .toHaveProperty('body', null)
    expect
      .soft(new FetchRequest(URL, { method: 'TRACK', body: 'hello' }))
      .toHaveProperty('body', null)

    expect
      .soft(new FetchRequest(URL, { method: 'POST', body: 'hello' }))
      .toHaveProperty('body', expect.any(ReadableStream))
  })
})

describe('FetchResponse', () => {
  it('clones a regular response', () => {
    const response = new Response('hello world')
    expect(FetchResponse.clone(response)).toMatchObject(response)
  })

  it('returns a mocked 500 response if cloning throws', async () => {
    const response = new Response('hello world')
    const error = new Error('Cannot clone!')
    response.clone = function () {
      throw error
    }

    const clone = FetchResponse.clone(response)
    expect.soft(clone.status).toBe(500)
    expect.soft(clone.statusText).toBe('Unclonable Response')
    await expect.soft(clone.json()).resolves.toEqual({
      name: error.name,
      message: error.message,
      stack: error.stack,
    })
  })

  it('sets the response URL', () => {
    const response = new Response('hello world')
    FetchResponse.setUrl('https://example.com/', response)

    expect(response.url).toBe('https://example.com/')
  })

  it('preserves a custom response URL after cloning Response', () => {
    const response = new FetchResponse('hello world')
    FetchResponse.setUrl('https://example.com/', response)

    expect(response.clone().url).toBe('https://example.com/')
  })

  it('preserves a custom response URL after cloning FetchResponse', () => {
    const response = new FetchResponse('hello world', {
      url: 'https://example.com/',
    })

    expect(response.clone().url).toBe('https://example.com/')
  })
})