storybook/docs/writing-tests/interaction-testing.md

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Interaction testing with Storybook

As you build more complex UIs like pages, components become responsible for more than just rendering the UI. They fetch data and manage state. Interaction tests allow you to verify these functional aspects of UI.

In a nutshell, you start by supplying the appropriate props for the initial state of a component. Then simulate user behavior such as clicks and form entries. Finally, test expectations to check whether the UI and component state update correctly.

Setup interactions addon

You can set up interaction testing in Storybook using the play function and @storybook/addon-interactions.

• play function is a convenient helper method to help test use cases that would otherwise require manual interaction from a user. They are small snippets of code that run after the story finishes rendering.

• @storybook/addon-interactions includes helper utilities and a playback interface that simulates user behavior in the browser. It’s powered Testing Library and includes convenient instrumentation for debugging.

Here's an example of how to set up interaction testing in Storybook with the play function:

<CodeSnippets paths={[ 'common/login-form-with-play-function.js.mdx', ]} />

Once the story loads in the UI, it simulates the user's behavior and verifies the underlying logic.

API for user-events

Under the hood, Storybook’s interaction addon mirrors Testing Library’s user-events API. If you’re familiar with Testing Library you should be at home in Storybook.

Below is an abridged API for user-event. For more, check out the official user-event docs.

User events	Description
clear	Selects the text inside inputs, or textareas and deletes it userEvent.clear(await within(canvasElement).getByRole('myinput'));
click	Clicks the element, calling a click() function userEvent.click(await within(canvasElement).getByText('mycheckbox'));
dblClick	Clicks the element twice userEvent.dblClick(await within(canvasElement).getByText('mycheckbox'));
deselectOptions	Removes the selection from a specific option of a select element userEvent.deselectOptions(await within(canvasElement).getByRole('listbox','1'));
hover	Hovers an element userEvent.hover(await within(canvasElement).getByTestId('example-test'));
keyboard	Simulates the keyboard events userEvent.keyboard(‘foo’);
selectOptions	Selects the specified option, or options of a select element userEvent.selectOptions(await within(canvasElement).getByRole('listbox'),['1','2']);
type	Writes text inside inputs, or textareas userEvent.type(await within(canvasElement).getByRole('my-input'),'Some text');
unhover	Unhovers out of element userEvent.unhover(await within(canvasElement).getByLabelText(/Example/i));

Running tests

In addition to interacting with the component using the play function, you can also write assertions to verify behavior. That offers a complete testing workflow without additional packages or configuration.

The example below showcases how a form component behaves when information is added.

<CodeSnippets paths={[ 'common/my-component-interaction-test-with-play-function.js.mdx', ]} />

When Storybook finishes rendering the story, it interacts with the component, fills in the form, simulates a button click, and verifies if the values returned match the provided ones.

Debugging

The @storybook/addon-interactions addon includes a set of UI controls to allow you control over the test execution flow. At any time, you can pause, resume, rewind, and step through each interaction. Also, providing you with an easy-to-use debugger for errors.

Open your Interactions panel and click on an individual step to jump to the exact state of the component when the interaction was triggered.

Permalinks for reproductions

The play function is executed after the story is rendered. If there’s an error, it’ll be shown in the interaction addon panel to help with debugging.

Since Storybook is a webapp, anyone with the URL can reproduce the error with the same detailed information without any additional environment configuration or tooling required.

Streamline interaction testing further by automatically publishing Storybook in pull requests. That gives teams a universal reference point to test and debug stories.

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What’s the difference between interaction tests and visual tests?

Interaction tests can be expensive to maintain when applied wholesale to every component. We recommend combining them with other methods like visual testing for comprehensive coverage with less maintenance work.

Learn about other UI tests

• Visual tests for appearance
• Accessibility tests for accessibility
• Interaction tests for user behavior simulation
• Snapshot tests for rendering errors and warnings
• Import stories in other tests for other tools