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    @jest-mock/express
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    1.4.1 • Public • Published

    @jest-mock/express

    A lightweight Jest mock for unit testing Express

    Build Status Coverage Status Known Vulnerabilities GitHub package.json version npm NPM

    Getting Started

    Installation:

    yarn add --dev @jest-mock/express

    npm install --save-dev @jest-mock/express

    Importing:

    import { getMockReq, getMockRes } from '@jest-mock/express'

    Usage

    Request - getMockReq

    getMockReq is intended to mock the req object as quickly as possible. In its simplest form, you can call it with no arguments to return a standard req object with mocked functions and default values for properties.

    const req = getMockReq()

    To create a mock req with provided values, you can pass them to the function in any order, with all being optional. The advantage of this is that it ensures the other properties are not undefined. Loose type definitions for standard properties are provided, custom properties ([key: string]: any) will be passed through to the returned req object.

    // an example GET request to retrieve an entity
    const req = getMockReq({ params: { id: '123' } })
    // an example PUT request to update a person
    const req = getMockReq({
      params: { id: 564 },
      body: { firstname: 'James', lastname: 'Smith', age: 34 },
    })

    For use with extended Requests, getMockReq supports generics.

    interface AuthenticatedRequest extends Request {
      user: User
    }
    
    const req = getMockReq<AuthenticatedRequest>({ user: mockUser })
    
    // req.user is typed
    expect(req.user).toBe(mockUser)

    Response - getMockRes

    getMockRes will return a mocked res object with Jest mock functions. Chaining has been implemented for the applicable functions.

    const { res, next, clearMockRes } = getMockRes()

    All of the returned mock functions can be cleared with a single call to mockClear. An alias is also provided called clearMockRes.

    const { res, next, mockClear } = getMockRes()
    
    beforeEach(() => {
      mockClear() // can also use clearMockRes()
    })

    It will also return a mock next function for convenience. next will also be cleared as part of the call to mockClear/clearMockRes.

    To create mock responses with provided values, you can provide them to the function in any order, with all being optional. Loose type definitions for standard properties are provided, custom properties ([key: string]: any) will be passed through to the returned res object.

    const { res, next, clearMockRes } = getMockRes({
      locals: {
        user: getLoggedInUser(),
      },
    })

    For use with extended Responses, getMockRes supports generics.

    interface CustomResponse extends Response {
      locals: {
        sessionId?: string
        isPremiumUser?: boolean
      }
    }
    
    const { res } = getMockRes<CustomResponse>({
      locals: {
        sessionId: 'abcdef',
        isPremiumUser: false,
      },
    })
    
    // res.locals is typed
    expect(res.locals.sessionId).toBe('abcdef')
    expect(res.locals.isPremiumUser).toBe(false)

    Example

    A full example to test a controller could be:

    // generate a mocked response and next function, with provided values
    const { res, next } = getMockRes({
      locals: {
        isPremiumUser: true,
      },
    })
    
    test('will respond with the entity from the service', async () => {
      // generate a mock request with params
      const req = getMockReq({ params: { id: 'abc-def' } })
    
      // provide the mock req, res, and next to assert
      await myController.getEntity(req, res, next)
    
      expect(res.json).toHaveBeenCalledWith(
        expect.objectContaining({
          id: 'abc-def',
        }),
      )
      expect(next).toBeCalled()
    })

    Install

    npm i @jest-mock/express

    DownloadsWeekly Downloads

    5,706

    Version

    1.4.1

    License

    MIT

    Unpacked Size

    348 kB

    Total Files

    39

    Last publish

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