@jest-mock/express

@jest-mock/express

A lightweight Jest mock for unit testing Express

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

getMockReq

getMockReq is intended to mock the req object as easily as possible. In its simplest form you can call it with no arguments to return a standard req with no values.

const mockReq = getMockReq()

To create mock requests with values you can just provide them to the function in any order and all are optional. The advantage of this is that it ensures all of the other properties are also provided with default values.

// an example GET request to retrieve an entity
const mockReq = getMockReq({ params: { id: '123' } })

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

getMockRes

getMockRes will provided a mocked res that will provided jest mock functions for all common requirements.

const mockRes = getMockRes()

All of the returned mocked functions can be cleared with a single call to mockClear.

beforeEach(() => {
  mockRes.mockClear()
})

It will also provide a mocked next function as that is commonly used and will also be cleared as part of mockClear.

const mockRes = getMockRes()

test('will respond with the entity from the service', async () => {
  // generate a mock request with getMockReq (above)
  const mockReq = getMockReq({ params: { id: '123' } })

  await myController.get(mockReq, mockRes.res, mockRes.next)

  expect(mockRes.res.json).toHaveBeenCalledWith({
    message: expect.any(String),
    entity: theExpectedEntity
  })
  expect(mockRes.next).toHaveBeenCalledWith()
})

Available Scripts

In the project directory, you can run:

yarn build

Transpiles the TypeScript source to the dist folder.

yarn clean

Clears the dist folder.

yarn test

Runs the tests and produces the coverage output.

yarn test-watch

Runs the tests in watch mode.

yarn lint

Runs the linter over the project.