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axios-mock-server

RESTful mock server using axios.

Features

• You can create a GET/POST/PUT/DELETE API endpoint in a few lines.
• A dedicated server is not required.
• It works with SPA as a static JavaScript file.
• You can use axios as mock-up even in Node.js environment.
• There is an auto-routing function similar to Nuxt.js, and no path description is required.
• Supports TypeScript.

Getting Started

Installation

• Using npm:

  1$ npm install axios
  2$ npm install axios-mock-server --save-dev

• Using Yarn:

  1$ yarn add axios
  2$ yarn add axios-mock-server --dev

Tutorial

Introducing the simplest use of axios-mock-server.

1$ mkdir mocks

1$ mkdir mocks/users
2$ touch mocks/users/_userId.js
3
4# If Windows (Command Prompt)
5> mkdir mocks\users
6> echo. > mocks\users\_userId.js

1// file: 'mocks/users/_userId.js'
2const users = [{ id: 0, name: 'foo' }, { id: 1, name: 'bar' }]
3
4module.exports = {
5  get({ values }) {
6    return [200, users.find(user => user.id === values.userId)]
7  }
8}

1$ node_modules/.bin/axios-mock-server
2
3# If Windows (Command Prompt)
4> node_modules\.bin\axios-mock-server

1$ cat mocks/\$mock.js
2/* eslint-disable */
3module.exports = (client) => require('axios-mock-server')([
4  {
5    path: '/users/_userId',
6    methods: require('./users/_userId')
7  }
8], client)
9
10# If Windows (Command Prompt)
11> type mocks\$mock.js

1// file: 'index.js'
2const axios = require('axios')
3const mock = require('./mocks/$mock.js')
4
5mock()
6
7axios.get('https://example.com/users/1').then(({ data }) => {
8  console.log(data)
9})

1$ node index.js
2{ id: 1, name: 'bar' }

Examples

axios-mock-server can be used to mock up browser usage, data persistence and multipart/form-data format communication.
It is also easy to link with Nuxt.js (@nuxtjs/axios).

See examples for source code.

Usage

Create an API endpoint

1const users = [{ id: 0, name: 'foo' }, { id: 1, name: 'bar' }]
2
3/**
4 * Type definitions for variables passed as arguments in requests
5 * @typedef { Object } MockMethodParams
6 * @property { import('axios').AxiosRequestConfig } config axios request settings
7 * @property {{ [key: string]: string | number }} values Dynamic value of the requested URL (underscore part of the path)
8 * @property {{ [key: string]: any }} params The value of the query parameter for the requested URL
9 * @property { any } data Request data sent by POST etc.
10 */
11
12/**
13 * Type definition when response is returned as an object
14 * @typedef { Object } MockResponseObject
15 * @property { number } status HTTP response status code
16 * @property { any? } data Response data
17 * @property {{ [key: string]: any }?} headers Response header
18 */
19
20/**
21 * Response type definition
22 * @typedef { [number, any?, { [key: string]: any }?] | MockResponseObject } MockResponse
23 */
24
25export default {
26  /**
27   * All methods such as GET and POST have the same type
28   * @param { MockMethodParams }
29   * @returns { MockResponse }
30   */
31  get({ values }) {
32    return [200, users.find(user => user.id === values.userId)]
33  },
34
35  /**
36   * You can also return a response asynchronously
37   * @param { MockMethodParams }
38   * @returns { Promise<MockResponse> }
39   */
40  async post({ data }) {
41    await new Promise(resolve => setTimeout(resolve, 1000))
42
43    users.push({
44      id: users.length,
45      name: data.name
46    })
47
48    return { status: 201 }
49  }
50}

Connect to axios

Default

axios-mock-server will mock up all axios communications by default.

1import axios from 'axios'
2import mock from './mocks/$mock.js'
3
4mock()
5
6axios.get('https://example.com/api/foo').then(response => {
7  /* ... */
8})

Each instance

You can also mock up each axios instance.

1import axios from 'axios'
2import mock from './mocks/$mock.js'
3
4const client = axios.create({ baseURL: 'https://example.com/api' })
5
6mock(client)
7
8client.get('/foo').then(response => {
9  /* ... */
10})
11
12// axios will not be mocked up
13axios.get('https://example.com/api/foo').catch(error => {
14  console.log(error.response.status) // 404
15})

Functions

axios-mock-server has several built-in functions available.

setDelayTime(millisecond: number): void

Simulate response delay.

1import axios from 'axios'
2import mock from './mocks/$mock.js'
3
4mock().setDelayTime(500)
5
6console.time()
7axios.get('https://example.com/api/foo').then(() => {
8  console.timeEnd() // default: 506.590ms
9})

enableLog(): void and disableLog(): void

Switch request log output.

1import axios from 'axios'
2import mock from './mocks/$mock.js'
3
4const mockServer = mock()
5
6;(async () => {
7  // To enable
8  mockServer.enableLog()
9  await axios.get('/foo', { baseURL: 'https://example.com/api', params: { bar: 'baz' } }) // stdout -> [mock] get: /foo?bar=baz => 200
10
11  // To disable
12  mockServer.disableLog()
13  await axios.get('/foo', { baseURL: 'https://example.com/api', params: { bar: 'baz' } }) // stdout ->
14})()

TypeScript

axios-mock-server includes TypeScript definitions.

Cautions

.gitignore

Exclude $mock.js or $mock.ts generated by axios-mock-server in the build from Git monitoring.

1$ echo "\$mock.*" >> .gitignore
2
3# If Windows (Command Prompt)
4> echo $mock.* >> .gitignore

@ts-ignore, eslint-disable

For TypeScript projects, add a // @ ts-ignore comment to the above line that imports$ mock.ts. If @typescript-eslint/ban-ts-ignore rule is enabled in typescript-eslint, please exclude the // @ ts-ignore comment from ESLint.

1// eslint-disable-next-line @typescript-eslint/ban-ts-ignore
2// @ts-ignore: Cannot find module
3import mock from './mocks/$mock'

Troubleshooting

The expected type comes from property 'get' which is declared here on type 'MockMethods' error in TypeScript

When returning a response asynchronously with TypeScript, an error occurs because the type does not match if you try to make the response an array.
Assert MockResponse or return it as an object.

Example of error (Note that the axios-mock-server build will pass!)

1import { MockMethods } from 'axios-mock-server'
2
3const methods: MockMethods = {
4  async get() {
5    await new Promise(resolve => setTimeout(resolve, 100))
6    return [200, { foo: 'bar' }] // Error
7  }
8}
9
10export default methods

Resolve by asserting MockResponse.

1import { MockMethods, MockResponse } from 'axios-mock-server'
2
3const methods: MockMethods = {
4  async get() {
5    await new Promise(resolve => setTimeout(resolve, 100))
6    return [200, { foo: 'bar' }] as MockResponse // Type safe
7  }
8}
9
10export default methods

If the response can be an object, no assertion is required.

1import { MockMethods } from 'axios-mock-server'
2
3const methods: MockMethods = {
4  async get() {
5    await new Promise(resolve => setTimeout(resolve, 100))
6    return { status: 200, data: { foo: 'bar' } } // Type safe
7  }
8}
9
10export default methods

Command Line Interface Options

The following options can be specified in the Command Line Interface.

Configuration

Settings are written in .mockserverrc file with JSON syntax.

License

axios-mock-server is licensed under a MIT License.