openapi-to-msw

A cli tool to generate random mock data from OpenAPI descriptions for msw and Storybook.

Usage

Install:

yarn add openapi-to-msw faker-js/faker -D

Read from your OpenAPI descriptions and output generated code:

# can be http url or a file path on your machine, support both yaml and json.
npx openapi-to-msw http://your_openapi.json -o ./mock.js

See here for Github API example. The msw mocking handlers was generated by following command:

npx openapi-to-msw https://raw.githubusercontent.com/github/rest-api-description/main/descriptions/ghes-3.3/ghes-3.3.json --output ./example/src/mock.ts

Integrate with msw, see Mock Service Worker's doc for more detail:

# Install msw
yarn add msw --dev

# Init service worker
npx msw init public/ --save

Then import those mock definitions in you app entry:

import { getHandlers } from "openapi-to-msw"
import { factories } from './mock';

if (process.env.NODE_ENV === 'development') {
  startWorker(getHandlers(factories));
}

Storybook Integration

// preview.js
import {
  initialize,
  mswDecorator,
} from "msw-storybook-addon";
import { getHandlersWithKey } from "openapi-to-msw"
import { factories } from './mock';

initialize();

export const parameters = {
  msw: {
    handlers: getHandlersWithKey(factories),
  },
};

// SomeComponent.stories.tsx
export default {
  component: SomeComponent,
}

export const Default: Story = {}

// for Error case
const customMockData = {
  ...
}

const customHandlers = getHandlersWithKey(customMockData, { statusCode: "error" })

export const Error: Story = {
  parameters: {
    msw: {
      handlers: {
        ...customHandlers
      }
    },
  },
}

Run you app then you'll see a successful activation message from Mock Service Worker in your browser's console.

Options

• -o, --output: specify output file path or output to stdout.
• -m, --max-array-length <number>: specify max array length in response, it'll cost some time if you want to generate a huge chunk of random data.
• -t, --match <keywords>: specify keywords to match if you want to generate mock data only for certain requests, multiple keywords can be seperated with comma.
• -h, --help: show help info.

Response Generation

• openapi-to-msw generates random value according to type, format, and x-faker property like Stoplight/Prism

Pet:
  type: object
  properties:
    id:
      type: integer
      format: int64
    name:
      type: string
      x-faker: name.firstName
      example: doggie
    photoUrls:
      type: array
      items:
        type: string
        x-faker: image.imageUrl

{
  "id": 12608726,
  "name": "Addison",
  "photoUrls": [
    "http://lorempixel.com/640/480",
    "http://lorempixel.com/640/480",
    "http://lorempixel.com/640/480",
    "http://lorempixel.com/640/480"
  ]
}