react-remock

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FYI: You can mock any React Component, rendered anywhere, and for the any reason.

Requires external configuration to work with React18 / jsx-runtime

This is like proxyquire, or jest.mock. Not for node.js, but for React. Pure React Dependency Injection.

• Every time you can NOT "storybook" something due to complexity.
• Every time you can NOT "enzyme" something, cos something deeply inside is "too smart" (and you can't use shallow).
• Every ^that^ time – mock the things you can NOT control.

Remock is based on the same technique, as React-Hot-Loader - intercepts React calls and do... whatever you want.

Use cases

This library was created for testing purposes only, while could be used to achive different tasks:

• Using remock with enzyme testing allows you to perform more shallow mount testing. You can just mock out, complitely remove some (deep nested internal) Component which could make testing harder. For example - Redux Connect, always seeking proper Provider.

• Using remock with storybooks testing allows you to hide some parts of "bigger", stories, leaving a holes in the story plot.

  • In case you are using BEM notation - it is really super easy to cat a hole, as long dimensions are propertly of a block, not element.
  • Yet again, in case of redux - you can replace connect by another component, to make it easier to provide mocked data for the story.

• Remock created not only for testing, but (even more) for hacking into components, and making pretty things.

Featured in

• (in)Finite War
• Why I Always Use Shallow Rendering

API

Play in codesandbox - https://codesandbox.io/s/xk7vp60o4

API is simple - it gets React.createElement as an input and returns React.createElement as an output. And it will be called when real React.createElement has been called.

If you will not return anything - element willbe completely mocked. In other cases - you could specify what to return.

 import {remock} from 'react-remock';

 remock.mock('ComponentName'); // you can mock by name
 remock.mock(/Connect\((.*)\)/); // you can mock by RegExp
 
 remock.mock(ComponentClass); // you can mock by class
 
 remock.mock({ propName:42 }); // you can mock by component props
 
 remock.transparent(Component); // replaces Component by () => children. Makes it "transparent"
 
 remock.renderProp(Component, ...arguments); // "unwraps" renderProp component, by calling function-as-children with provided arguments 
 
 remock.match((type, props, children) => true); // you can mock using user-defined function
 
 remock.mock(Component, (type, props, children) => ({type?, props?, children?})); // you can alter rendering
 
 // unmock any mock `like` this
 remock.unmock('ComponentName' | ComponentName);
 
 const unmock = remock.mock(ComponentClass);
 // remove mock this mock only
 unmock();
 
 // and dont forget to
 remock.clearMock();

 // "scoped" mocks for local cleanups 
 remock.push();
 remock.mock('anything')
 remock.pop();

 
 
 // You can also use "declarative" React API. (only with mount!)
 // mocking has a global effect, `Remocking` would only automate cleanup
 mount(
   <div>
       <Remocking component="Red" />
       <Red />
   </div>
 );

PS: preact support it yet untested

Additional API

import {createElement, enable, disable} from 'react-remock';

createElement() // is a "real" React.createElement;

disable() ;// you can always disable rewiremock as a whole
enable(); // and enable it back

React 18

Out of the box Remock does not support React 18 to maintain backward compatibility. Currently, you have to patch jsx-runtime at the user side

// import jsx runtime
import jsxRuntime from "react/jsx-runtime";
import jsxRuntimeDev from "react/jsx-dev-runtime";

// import patch helper
import {patchJsxRuntime} from 'react-remock';

// apply the patch
patchJsxRuntime(jsxRuntime);
patchJsxRuntime(jsxRuntimeDev);

This may be fixed in the future versions

Dev/Production

The best way - not to use remock, and not require it in production.

If that is undoable - use "dev" exports, which will return mocked API for production builds.

import {remock} from 'remock/dev';

// you still can run all the commands
// but remock core does not exists.
remock.mock(...);

More examples

// change prop on Hello
remock.mock(Hello, () => ({props:{name:"Remock"}}))

// change h2 to h3, change style, change children
remock.mock('h2', (type, props, children) => { 
  return ({
  type: 'h4',
  props: {
    ...props,
    style: {color:'#700'},   
  },
  children: `🧙️ ${children} 🛠`
})})

// wrap divs with a border
remock.mock('div', (type, props) => ({
  props: {
    ...props,
    style:{
      ...props.style,
      border:'1px solid #000'
    },
  }
}));

Why you may need it?

• to empower shallow rendering Why I Always Use Shallow Rendering
• to wrap your components with another components, you were able to do with jquery - see examples for react-queue
• color React-Dev-Tools, helping distinquish Stateful/SFC and RenderProps? code-sandboxexample.

See also

Remock is a little brother of rewiremock

Licence

MIT

Happy mocking!