msw-react

A small library to easily integrate msw with react.

Why

You can use this utility to test your React components without the need of a backend server. It wraps msw, so you can refer to the documentation here.

Features

• Small and lightweight
• Built-in Typescript support

Installation

npm install -s msw-react
or
yarn add msw-react
or
pnpm install msw-react

Initialize

As said before this utility is essentially a react wrap for the msw library, this means that to make it work on the client a Service Worker needs to be created.

To do so, just run npx msw init <public_dir> --save where <public_dir> corresponds to the public directory of your project:

npx msw init ./public --save
or
pnpx msw init ./public --save

Usage

Wrap your code in MockProvider component to make the worker instance available to all the sub components.

MockProvider

handlers

const handlers = [
  rest.get("https://github.com/octocat", (req, res, ctx) => {
    return res(
      ctx.delay(1500),
      ctx.status(202, "Mocked status"),
      ctx.json({
        message: "Mocked response JSON body",
      })
    );
  }),
];

<MockProvider handlers={handlers}>
  <App />
</MockProvider>

startOnMount

By default it will start the worker server on mount, you can override this behavior using the startOnMount boolean prop.

<MockProvider handlers={handlers} startOnMount={false}>
  <App />
</MockProvider>

startOptions

Or if you wanna pass some custom options to the start method you can pass them as startOptions prop. Take a look here for a list of all the available options

<MockProvider handlers={} startOptions={{ quiet: true, waitUntilReady: true }}>
  <App />
</MockProvider>

enabled

By default the Service Worker gets setup only on the Development mode, but it allows you to control it using the enabled prop which as suggested by msw defaults to process.env.NODE_ENV === "development"

<MockProvider handlers={handlers} enabled={false}>
  <App />
</MockProvider>

setupServer

We give you also access to override the default setupServer function (which defaults to the msw implementation)

const customSetupServer = (handlers) => {
  doSomethingElse();
  setupServer(...handlers);
};

<MockProvider handlers={handlers} setupServer={customSetupServer}>
  <App />
</MockProvider>

useWorker - MswWorker

Each child of the MockProvider will have access to the worker instance. Either by using the useWorker hook:

import { useWorker } from "msw-react";
const Child = () => {
  const worker = useWorker();
  useEffect(() => {
    worker.stop();
  }, []);

  return <div>Hello</div>;
};

Or using the MswWorker component:

import { MswWorker } from 'msw-react';
const Child2 = () => {
  return (
    <MswWorker>
      {(worker) => (
        <>Hello<>
      )}
    </MswWorker>
  );
}

Examples

The advantage of being a simple wrap of msw is that it works out of the box with other libraries that implement msw's API, some examples:

• ts-mckr:

// Import
import dbUtils, { MockServer, MockServerInit } from "ts-mckr";

// Import static data
import quotes from "./quotes.json";

// Database creation
const mockDb = {
  quotes: {
    id: dbUtils.primaryKey(Number),
    quote: String,
    author: String,
  },
  users: {
    id: dbUtils.primaryKey(Number),
    name: String,
  },
};

const handlers = new MockServer()
  // Database init
  .createDB(mockDb)
  // Dataset injection, using fake data
  .createDataSet(
    {
      users: [
        {
          name: MockServer.getFakeData({
            module: "name",
            method: "fullName",
            language: "it",
          }),
          birthDate: MockServer.getFakeData({
            module: "date",
            method: "birthdate",
          }),
        },
      ],
    },
    // Dataset options
    { repeat: 40 }
  )
  // Dataset injection, using json data (static)
  .createDataSet({ quotes })
  // Get handlers (get, post, ecc...)
  .createHandlers();

// Create worker

return (
  <MockProvider handlers={handlers} setupServer={MockServerInit}>
    <App />
  </MockProvider>
);