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@muban/testing-library

Introduction

Muban Testing Library builds on top of DOM Testing Library by adding APIs for working with Muban components.

Since muban components require both a Component and a Template to be provided separately, we chose to leverage the Story format from @muban/storybook to render these components.

In short, Muban Testing Library does three things:

  • Re-exports query utilities and helpers from DOM Testing Library.
  • Provides a render function to render a Muban component
  • Binds all the query functions to the rendered component template.

Quick start

Add @muban/testing-library to your project:

npm i -D @muban/testing-library
yarn add -D @muban/testing-library

You can now use all of DOM Testing Library's getBy, getAllBy, queryBy and queryAllBy commands. See here the full list of queries.

You may also be interested in installing @testing-library/jest-dom so you can use the custom Jest matchers for the DOM.

API

render

Renders a Muban Story into the (virtual) DOM, and returns @testing-library/dom helpers, alongside with some debug functions, and the byRef helpers.

function render<T extends StoryFn | StoryObj>(
  componentFactory: T,
  templateData?: StoryArgs<T>,
)

Parameters

  • componentFactory – An StoryObj or StoryFn Muban story to render.
  • templateData – The storybook args that are used by the template to render dynamic parts.

Returns

  • container – a wrapper div that is used to render the story in.
  • debug(element) – A function to output the DOM in a formatted way.
  • html() – A function that outputs the outerHTML of the container.
  • unmount() - A function to remove the container from the DOM again, which should unmount the attached component as well.
  • ...queries – All query functions from @testing-library/dom + the byRef functions from this package, all bound to the rendered component container.
// render the story component
const { queryByRef } = render(StoryItem, { param: 'value'});

// query al element inside the story container
const element = queryByRef('item');

byRef

The following query functions can be used to query elements by their data-ref attribute. Even though this is not recommended, and goes against the philosophy of testing-library, we still want to offer these in case of need, since they are a big part of how Muban itself queries elements. You could compare them with data-testid in that way, which does have supported queries.

  • queryByRef
  • queryAllByRef
  • getByRef
  • getAllByRef

How they work in certain situations is explained here.

import {queryByRef, queryAllByRef} from '@muban/testing-library';

// container = <span data-ref="item">test</span>
const element = queryByRef(container, 'item');

// container = <div>
//  <span data-ref="item">test</span>
//  <span data-ref="item">test</span>
// </div>
const elements = queryAllByRef(container, 'item');

Use Cases

In Unit Tests

This is the core use case of this library. In each test you want to render a component, and used the returned queries to retrieve elements to interact with or assert correctness.

Then use the @testing-library/dom helpers to interact with these elements, and use jest and the @testing-library/jest-dom matchers to manage your expectations.

When possible, you want to re-use your stories to execute these tests on.

In the Storybook Play function

Storybook has a play function that allows you to interact with your stories.

The recommended use case is to interact with the element provided to the play function, using the functions from the @storybook/testing-library package. This is a re-export of the normal @testing-library/dom package, but instrumentation is added to show all interactions in the interactions panel. This panel is available when you add the @storybook/addon-interactions addon.

The queries exported by this library (e.g. queryByRef) are not bound to that element, and also not instrumented. You can still use them the normal way, by manually providing the container element as the first parameter, but they won't show up in the interactions panel.

Examples

TODO