Mihawk (simple tiny mock-server)

🇨🇳 中文版说明 → README.zh-CN.md

Recommend: use version@v1.0.0+

Make a easy mock-server to mock api, with GET /a/b/c → ./mocks/data/GET/a/b/c.json mapping

• ✔️ Zero intrusion into front-end code
• ✔️ Support https protocol
• ✔️ Support all methods, like GET, POST, PUT, DELETE etc.
• ✔️ Support mock data file type: json | json5
• ✔️ Support custom your middleware in middleware.{js|cjs|ts}, write as koa2 middleware (or express-middleware both ok with func.isExpress=true)
• ✔️ Support custom special routes mapping in routes.json, mapping multiple request to same resolve file。 routes key align glob expression
• ✔️ Support mock logic file type: js | cjs | ts
• ✔️ Slightly support for socket simulations
• ✔️ Support the generation of some simple simulation data, in mihawk/tools, eg: createRandPhone、createRandEmail

Install

npm i -g mihawk

Usage

mihawk --port=8888
# mihawk -p 8888

then open browser and visit http://localhost:8888

mock data directory: ./mocks/data

./mocks
    │
    ├── /data
    │   │
    │   ├── DELETE
    │   │     ├──/*.js    DELETE request resolve logic
    │   │     └──/*.json  DELETE request resolve data
    │   │
    │   ├── GET
    │   │     ├──/*.js    GET request resolve logic
    │   │     └──/*.json  GET request resolve data
    │   │
    │   ├── POST
    │   │     ├──/*.js    POST request resolve logic
    │   │     └──/*.json  POST request resolve data
    │   │
    │   └── PUT
    │         ├──/*.js    PUT request resolve logic
    │         └──/*.json  PUt request resolve data
    │
    ├── middleware.js    [optional] resolve middleware
    │
    └── routes.json   [optional] common routes

mapping：

request    ： GET http://localhost:8888/a/b/c/d
JSON-file  ： data/get/a/b/c/d.json
mock-file  :  data/get/a/b/c/d.js

• request: mock request url
• JSON-file: mock origin data
• mock-file: resolve mock logic, base on origin data

Finally, the return data will be the data after processing mock-file (the mock-file) with origin data (the JSON-file)

Usage-Recommend ✅

A more recommended way to use it is to write all config props into the .mihawkrc.json in the root directory

And then run mihawk in you shell

init a rc file .mihawkrc.json

mihawk init

then edit the .mihawkrc.json to customize your config

{
  "host": "0.0.0.0",
  "port": 8888,
  "https": false,
  "cors": true,
  "cache": true,
  "watch": true,
  "mockDir": "mocks",
  "mockDataFileType": "json",
  "mockLogicFileType": "none"
}

About root config props:

• host: string, default 0.0.0.0, server listen on this host
• port: number, default 8888, server listen on this port
• https: boolean, default false, if true, will use https protocol
• cors: boolean, default true, if true, will add Access-Control-Allow-Origin: * (and other necessary cors props in headers ) to the response headers
• cache: boolean, default true, if true, will cache the mock data and return the cached data when the request is the same
• watch: boolean, default true, if true, will watch the mock data directory and reload when changed
• mockDir: string, default mocks, the directory of mock data
• mockDataFileType: string json | json5, default json, the file type of mock data
• mockLogicFileType: string js | cjs | ts | none, default none, the file type of mock logic
• setJsonByRemote: { enable: boolean; target: string; timeout?: number; rewrite?: (path: string) => string } | null
  • Default: undefined
  • When local mock file not found:
    1. If set to proxy object with {enable:true, target:'xxx' } to fetch from remote proxy
    2. If set to null/undefined to disable
  • Proxy config requires:
    • target(required): remote server URL, required
    • rewrite: optional path rewrite function
    • timeout: request timeout in milliseconds

More detail → src/com-types.ts, interface MihawkRC define the config props

Config with Build tools

graph LR
    A[Dev Mode: Request] --> B(devServer)
    B --> D1[Mode 1: mockServer → Local launched mockServer]
    B --> D2[Mode 2: Proxy to backend → Change proxy to backend's address]
    D1 --> C(Mihawk)
    D2 --> E(BackendServer)

    F[Production Mode: Request] --> G(BackendServer)

    style A fill:#2c2c2c,stroke:#ccc,fill-opacity:1,color:#eee
    style B fill:#5e6472,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0
    style C fill:#09c,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0
    style D1 fill:#5e6472,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0
    style D2 fill:#5e6472,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0
    style E fill:#7a6da2,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0
    style F fill:#2c2c2c,stroke:#ccc,fill-opacity:1,color:#eee
    style G fill:#7a6da2,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0

    classDef devStyle fill:#2c2c2c,stroke:#ccc,fill-opacity:1,color:#eee;
    classDef serviceStyle fill:#5e6472,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0;
    classDef backendStyle fill:#7a6da2,stroke:#f0f0f0,fill-opacity:1,color:#f0f0f0;

    class A,F devStyle
    class B,D1,D2 serviceStyle
    class C,E,G backendStyle

Loading

In the above diagram, devServer is typically provided by bundling tools during local development, such as Vite or Webpack, which have corresponding configuration options.

Essentially, it is based on the proxy functionality of devServer, forwarding requests to the mihawk server.

vite

in vite.config.js file:

import { defineConfig } from 'vite';
export default defineConfig({
  server: {
    proxy: {
      '/api': {
        target: 'http://localhost:8888', // mihawk server address
        changeOrigin: true,
        rewrite: path => path.replace(/^\/api/, ''),
      },
    },
  },
});

webpack

in webpack.config.js file:

// webpack.config.js
module.exports = {
  devServer: {
    proxy: {
      '/api': {
        target: 'http://localhost:8888', // mihawk server address
        changeOrigin: true,
        pathRewrite: { '^/api': '' },
      },
    },
  },
};

Example

For request GET /api/fetch_a_random_number，it return response with random number data

1.create mocks/data/GET/api/fetch_a_random_number.json file, content as below

{
  "code": 200,
  "data": 123456,
  "msg": "success"
}

You cal aslo dont do this step, coz the mock data file is auto create when request a not exists file

Now, if request GET /api/fetch_a_random_number，return data is 123456, it is fixed data

2.create mocks/data/GET/api/fetch_a_random_number.js file, content as below

module.exports = async function (oldJson) {
  oldJson.data = Math.floor(Math.random() * 1000000); // generate random number
  return oldJson; // return data, it is required
};

Start mihawk server now, if request GET /api/fetch_a_random_number，return data is random number, each request return a different data

About MockLogic File:

• Both support js | cjs | ts, the process is same。Attention to export default is necessary in ts file!
• Recommend to set autoCreateMockLogicFile to true in .mihawkrc.json, then, if request a not exists mock data file, it will auto create a mock logic file for you
• Of course, it is worth mentioning that MockLogic files aren't necessary files. If there is no logical demand for data processing, using only JSON files can also simulate the request

More example of mocks files

routes file demo in ts

/**
 * mihawk's routes file:
 */
const routes: Record<string, string> = {
  'GET /test': './GET/test',
  'GET /test-*': './GET/test', // key: routePath，support glob expression; value:  mock data file path (no ext)
};
//
export default routes;

middleware file demo in ts

/**
 * mihawk's middleware file:
 * - just a Koa2 Middleware
 */
import type { Context: KoaContext, Next: KoaNext } from 'koa'; // need koa@v2.0.0+ (eg: koa@^2.15.3)
// import type { KoaContext, KoaNext } from 'mihawk/con-types';

/**
 * Middleware functions, to implement some special data deal logic,
 * - This function exec before the default-mock-logic. Simply return or don`t call "await next()" could skip default-mock-logic
 * - This function is a standard KOA middleware that follows the KOA onion ring model
 * - see more：https://koajs.com/#middleware
 * @param {Context} ctx
 * @param {Next} next
 * @returns {Promise<void>}
 */
export default async function middleware(ctx: KoaContext, next: KoaNext) {
  // do something here
  console.log(ctx.url);
  if (ctx.peth === '/diy') {
    ctx.body = 'it is my diy logic';
  } else {
    await next(); // default logic (such like mock json logic)
  }
}

Set middleware.isExpress=true to explicit definition a express middleware function before export, if you write in express-stype Other complex diy middleware demo, base on koa-router & koa-compose, middleware.md

mock-logic file demo in ts

'use strict;';
/**
 * GET /xxx
 * This file isn‘t mandatory. If it is not needed (such as when there is no need to modify response data), it can be deleted directly
 */

/**
 * Mock data resolve function, the original data source is the JSON file with the same name as this file
 * @param {object} originData (mocks/data/GET/xxx.json)
 * @param {MhkCvtrExtra} extra { url,method,path,query,body }
 * @returns {object} newData
 */
export default async function convertData(originData: Record<string, any>, extra: Record<string, any>) {
  // write your logic here...
  originData.newProp = 'newPropXxx';
  return originData; // return data, it is required
}

Differences from Mockjs?

1. Different positioning

• Mockjs is a front-end mockjs library that provides powerful simulated data generation capabilities
• Mihawk is a Node.js mock service that can be used with front-end projects or standalone; it provides mock capabilities for httpServer/SocketServer based on Nodejs

2. Different implementation methods

• Mockjs intercepts requests and returns simulated data by hijacking xhr/fetch, etc., which requires certain modifications to front-end engineering code, and there are some differences in the request sending/receiving process compared to the real online environment
• Mihawk intercepts requests and returns simulated data through Koa2 middleware format, without requiring any modifications to front-end engineering code, and the request sending/receiving process is identical to the real online environment

3. Common usage scenarios

• Mockjs is used for simulated data production, generating corresponding fake data through its specific syntax
• Mihawk is used to simulate BackendServer based on Nodejs, such as Socket, httpServer, etc., combined with simple data generation functions to complete fake data generation
  • mhiawk/tools: Built-in utility functions like creatRandXxx for generating fake data; this functionality is not as powerful as Mockjs
    • Consider using both mockjs's data generate and mihawk's server mock together; they are not mutually exclusive
  • your_project/mocks/middleware.ts: Simulate backend services, such as httpServer
  • your_project/mocks/socket.ts: Simulate backend services, such as socketServer