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https://github.com/storybookjs/testing-react

Testing utilities that allow you to reuse your Storybook stories in your React unit tests!
https://github.com/storybookjs/testing-react

react storybook testing testing-library

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Testing utilities that allow you to reuse your Storybook stories in your React unit tests!

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README 

        


  Storybook React Testing




Testing utilities that allow you to reuse your stories in your unit tests







## ⚠️ Attention!



If you're using Storybook 7, you need to read this section. Otherwise, feel free to skip it.



`@storybook/testing-react` has been promoted to a first-class Storybook functionality. This means that **you no longer need this package**. Instead, you can import the same utilities, but from the `@storybook/react` package. Additionally, the internals of `composeStories` and `composeStory` have been revamped, so the way a story is composed is more accurate. The `@storybook/testing-react` package will be deprecated, so we recommend you to migrate.



Please do the following:



1. Uninstall this package

2. Update your imports



```diff

- import { composeStories } from '@storybook/testing-react';

+ import { composeStories } from '@storybook/react';



// OR

- import { setProjectAnnotations } from '@storybook/testing-react';

+ import { setProjectAnnotations } from '@storybook/react';

```



## The problem



You are using [Storybook](https://storybook.js.org/) for your components and writing tests for them with [jest](https://jestjs.io/), most likely alongside [Enzyme](https://enzymejs.github.io/enzyme/) or [React testing library](https://testing-library.com/). In your Storybook stories, you already defined the scenarios of your components. You also set up the necessary decorators (theming, routing, state management, etc.) to make them all render correctly. When you're writing tests, you also end up defining scenarios of your components, as well as setting up the necessary decorators. By doing the same thing twice, you feel like you're spending too much effort, making writing and maintaining stories/tests become less like fun and more like a burden.



## The solution



`@storybook/testing-react` is a solution to reuse your Storybook stories in your React tests. By reusing your stories in your tests, you have a catalog of component scenarios ready to be tested. All [args](https://storybook.js.org/docs/react/writing-stories/args) and [decorators](https://storybook.js.org/docs/react/writing-stories/decorators) from your [story](https://storybook.js.org/docs/react/api/csf#named-story-exports) and its [meta](https://storybook.js.org/docs/react/api/csf#default-export), and also [global decorators](https://storybook.js.org/docs/react/writing-stories/decorators#global-decorators), will be composed by this library and returned to you in a simple component. This way, in your unit tests, all you have to do is select which story you want to render, and all the necessary setup will be already done for you. This is the missing piece that allows for better shareability and maintenance between writing tests and writing Storybook stories.



## Installation



This library should be installed as one of your project's `devDependencies`:



via [npm](https://www.npmjs.com/)



```

npm install --save-dev @storybook/testing-react

```



or via [yarn](https://classic.yarnpkg.com/)



```

yarn add --dev @storybook/testing-react

```



## Setup



### Storybook 6 and Component Story Format



This library requires you to be using Storybook version 6, [Component Story Format (CSF)](https://storybook.js.org/docs/react/api/csf) and [hoisted CSF annotations](https://github.com/storybookjs/storybook/blob/next/MIGRATION.md#hoisted-csf-annotations), which is the recommended way to write stories since Storybook 6.



Essentially, if you use Storybook 6 and your stories look similar to this, you're good to go!



```jsx

// CSF: default export (meta) + named exports (stories)

export default {

  title: 'Example/Button',

  component: Button,

};



const Primary = args => ; // or with Template.bind({})

Primary.args = {

  primary: true,

};

```



### Global config



> This is an optional step. If you don't have [global decorators](https://storybook.js.org/docs/react/writing-stories/decorators#global-decorators), there's no need to do this. However, if you do, this is a necessary step for your global decorators to be applied.



If you have global decorators/parameters/etc and want them applied to your stories when testing them, you first need to set this up. You can do this by adding to or creating a jest [setup file](https://jestjs.io/docs/configuration#setupfiles-array):



```tsx

// setupFile.js <-- this will run before the tests in jest.

import { setProjectAnnotations } from '@storybook/testing-react';

import * as globalStorybookConfig from './.storybook/preview'; // path of your preview.js file



setProjectAnnotations(globalStorybookConfig);

```



For the setup file to be picked up, you need to pass it as an option to jest in your test command:



```json

// package.json

{

  "test": "react-scripts test --setupFiles ./setupFile.js"

}

```



## Usage



### `composeStories`



`composeStories` will process all stories from the component you specify, compose args/decorators in all of them and return an object containing the composed stories.



If you use the composed story (e.g. PrimaryButton), the component will render with the args that are passed in the story. However, you are free to pass any props on top of the component, and those props will override the default values passed in the story's args.



```tsx

import { render, screen } from '@testing-library/react';

import { composeStories } from '@storybook/testing-react';

import * as stories from './Button.stories'; // import all stories from the stories file



// Every component that is returned maps 1:1 with the stories, but they already contain all decorators from story level, meta level and global level.

const { Primary, Secondary } = composeStories(stories);



test('renders primary button with default args', () => {

  render();

  const buttonElement = screen.getByText(

    /Text coming from args in stories file!/i

  );

  expect(buttonElement).not.toBeNull();

});



test('renders primary button with overriden props', () => {

  render(Hello world); // you can override props and they will get merged with values from the Story's args

  const buttonElement = screen.getByText(/Hello world/i);

  expect(buttonElement).not.toBeNull();

});

```



### `composeStory`



You can use `composeStory` if you wish to apply it for a single story rather than all of your stories. You need to pass the meta (default export) as well.



```tsx

import { render, screen } from '@testing-library/react';

import { composeStory } from '@storybook/testing-react';

import Meta, { Primary as PrimaryStory } from './Button.stories';



// Returns a component that already contain all decorators from story level, meta level and global level.

const Primary = composeStory(PrimaryStory, Meta);



test('onclick handler is called', () => {

  const onClickSpy = jest.fn();

  render();

  const buttonElement = screen.getByRole('button');

  buttonElement.click();

  expect(onClickSpy).toHaveBeenCalled();

});

```



### setting project annotations to `composeStory` or `composeStories`



`setProjectAnnotations` is intended to apply all the global configurations that are defined in your `.storybook/preview.js` file. This means that you might get unintended side-effects in case your preview.js imports certain mocks or other things you actually do not want to execute in your test files. If this is your case and you still need to provide some annotation overrides (decorators, parameters, etc) that normally come from preview.js, you can pass them directly as the optional last argument of both `composeStories` and `composeStory` functions:



**composeStories**:



```ts

import * as stories from './Button.stories'



// default behavior: uses overrides from setProjectAnnotations

const { Primary } = composeStories(stories)



// custom behavior: uses overrides defined locally

const { Primary } = composeStories(stories, { decorators: [...], globalTypes: {...}, parameters: {...})

```



**composeStory**:



```ts

import * as stories from './Button.stories'



// default behavior: uses overrides from setProjectAnnotations

const Primary = composeStory(stories.Primary, stories.default)



// custom behavior: uses overrides defined locally

const Primary = composeStory(stories.Primary, stories.default, { decorators: [...], globalTypes: {...}, parameters: {...})

```



### Reusing story properties



The components returned by `composeStories` or `composeStory` not only can be rendered as React components, but also come with the combined properties from story, meta and global configuration. This means that if you want to access `args` or `parameters`, for instance, you can do so:



```tsx

import { render, screen } from '@testing-library/react';

import { composeStory } from '@storybook/testing-react';

import * as stories from './Button.stories';



const { Primary } = composeStories(stories);



test('reuses args from composed story', () => {

  render();



  const buttonElement = screen.getByRole('button');

  // Testing against values coming from the story itself! No need for duplication

  expect(buttonElement.textContent).toEqual(Primary.args.children);

});

```



### CSF3



Storybook 6.4 released a [new version of CSF](https://storybook.js.org/blog/component-story-format-3-0/), where the story can also be an object. This is supported in `@storybook/testing-react`, but you have to match one of the requisites:



1 - Your **story** has a `render` method

2 - Or your **meta** has a `render` method

3 - Or your **meta** contains a `component` property



```js

// Example 1: Meta with component property

export default {

  title: 'Button',

  component: Button, // <-- This is strictly necessary

};



// Example 2: Meta with render method:

export default {

  title: 'Button',

  render: args => ,

};



// Example 3: Story with render method:

export const Primary = {

  render: args => ,

};

```



#### Interactions with play function



Storybook 6.4 also brings a new function called `play`, where you can write automated interactions to the story.



In `@storybook/testing-react`, the `play` function does not run automatically for you, but rather comes in the returned component, and you can execute it as you please.



Consider the following example:



```tsx

export const InputFieldFilled: Story = {

  play: async ({ canvasElement }) => {

    const canvas = within(canvasElement);

    await userEvent.type(canvas.getByRole('textbox'), 'Hello world!');

  },

};

```



You can use the play function like this:



```tsx

const { InputFieldFilled } = composeStories(stories);



test('renders with play function', async () => {

  const { container } = render();



  // pass container as canvasElement and play an interaction that fills the input

  await InputFieldFilled.play({ canvasElement: container });



  const input = screen.getByRole('textbox') as HTMLInputElement;

  expect(input.value).toEqual('Hello world!');

});

```



## Batch testing all stories from a file



Rather than specifying test by test manually, you can also run automated tests by using [test.each](https://jestjs.io/docs/api#testeachtablename-fn-timeout) in combination with `composeStories`. Here's an example for doing snapshot tests in all stories from a file:



```js

import * as stories from './Button.stories';



const testCases = Object.values(composeStories(stories)).map((Story) => [

  // The ! is necessary in Typescript only, as the property is part of a partial type

  Story.storyName!,

  Story,

]);

// Batch snapshot testing

test.each(testCases)('Renders %s story', async (_storyName, Story) => {

  const tree = await render();

  expect(tree.baseElement).toMatchSnapshot();

});

```



## Typescript



`@storybook/testing-react` is typescript ready and provides autocompletion to easily detect all stories of your component:



![component autocompletion](./assets/autocompletion-compose.png)



It also provides the props of the components just as you would normally expect when using them directly in your tests:



![props autocompletion](./assets/autocompletion-props.png)



Type inference is only possible in projects that have either `strict` or `strictBindApplyCall` modes set to `true` in their `tsconfig.json` file. You also need a TypeScript version over 4.0.0. If you don't have proper type inference, this might be the reason.



```jsonc

// tsconfig.json

{

  "compilerOptions": {

    // ...

    "strict": true, // You need either this option

    "strictBindCallApply": true // or this option

    // ...

  }

  // ...

}

```



### Disclaimer



For the types to be automatically picked up, your stories must be typed. See an example:



```tsx

import React from 'react';

import { Story, Meta } from '@storybook/react';



import { Button, ButtonProps } from './Button';



export default {

  title: 'Components/Button',

  component: Button,

} as Meta;



// Story is the key piece needed for typescript validation

const Template: Story = args => ;



export const Primary = Template.bind({});

Primary.args = {

  children: 'foo',

  size: 'large',

};

```



## License



[MIT](./LICENSE)