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https://github.com/bikk-uk/jest-mock-express
A lightweight Jest mock for unit testing Express
https://github.com/bikk-uk/jest-mock-express
Last synced: 3 days ago
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A lightweight Jest mock for unit testing Express
- Host: GitHub
- URL: https://github.com/bikk-uk/jest-mock-express
- Owner: bikk-uk
- License: mit
- Created: 2019-10-19T10:32:15.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2024-11-21T21:17:08.000Z (22 days ago)
- Last Synced: 2024-11-29T11:55:38.234Z (15 days ago)
- Language: TypeScript
- Size: 1.05 MB
- Stars: 51
- Watchers: 3
- Forks: 7
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-jest - @jest-mock/express
README
# @jest-mock/express
A lightweight Jest mock for unit testing Express
[](https://github.com/bikk-uk/jest-mock-express/actions/workflows/build-test.yml)
[](https://coveralls.io/github/bikk-uk/jest-mock-express?branch=master)
[](https://snyk.io/test/github/bikk-uk/jest-mock-express?targetFile=package.json)
## Getting Started
Installation:
`yarn add --dev @jest-mock/express`
`npm install --save-dev @jest-mock/express`
Importing:
```typescript
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.
```typescript
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.
```typescript
// an example GET request to retrieve an entity
const req = getMockReq({ params: { id: '123' } })
```
```typescript
// 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.
```typescript
interface AuthenticatedRequest extends Request {
user: User
}
const req = getMockReq({ 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.
```typescript
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`.
```typescript
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.
```typescript
const { res, next, clearMockRes } = getMockRes({
locals: {
user: getLoggedInUser(),
},
})
```
For use with extended Responses, `getMockRes` supports generics.
```typescript
interface CustomResponse extends Response {
locals: {
sessionId?: string
isPremiumUser?: boolean
}
}
const { res } = getMockRes({
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:
```typescript
// 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()
})
```