storybook-addon-vis
v0.13.0
Published
Storybook Vitest Image Snapshot addon
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storybook-addon-vis
Storybook Vitest Image Snapshot add-on.
Captures and compare image snapshot automatically and manually.
This add-on is inspired by jest-image-snapshot.
Starting from storybook 8.3, you can run Storybook stories with vitest browser mode.
Since it is running in actual browser, jest-image-snapshot does not work. This add-on provides similar functionality to jest-image-snapshot. In addition, you can capture image snapshot manually.
Install
npm install --save-dev storybook-addon-vis
pnpm add --save-dev storybook-addon-vis
yarn add --save-dev storybook-addon-vis
Config
This add-on provides features on both storybook and vitest, thus you need to add it to both storybook and vitest.
On vitest, you need to add storybook-addon-vis/vitest-plugin
plugin in vitest.config.ts
.
// vite.config.ts or vitest.config.ts
import { storybookTest } from '@storybook/experimental-addon-test/vitest-plugin'
import { storybookVis } from 'storybook-addon-vis/vitest-plugin'
import { defineConfig } from 'vitest/config'
export default defineConfig({
plugins: [
storybookTest(),
storybookVis()
],
test: {
browser: {
// ...
},
global: false, // recommend to set to false
setupFiles: ['./vitest.setup.ts'],
}
})
Note that we recommend to set global
to false
.
Setting global
to true
actually works ok during test,
although you need to access the functions from the globalThis
or window
object.
However, the problem is when the story is run within storybook.
In storybook, the global
field has no effect.
And in fact, you need to import the functions from @storybook/test
instead:
// some.test.ts
import { expect } from 'vitest'
// some.stories.ts
import { expect } from '@storybook/test'
Therefore, to avoid confusion, we recommend to set global
to false
.
In vitest.setup.ts
, you can use one of the presets to do the setup for you.
You can also use the provided hooks to set up the test environment manually.
// vitest.setup.ts
import { setProjectAnnotations } from '@storybook/react'
import { createVisConfig } from 'storybook-addon-vis/vitest-setup'
import * as projectAnnotations from './preview'
const project = setProjectAnnotations([projectAnnotations])
// capture image snapshot for all stories with `snapshot` tag
createVisConfig(/* options */).presets.basic()
// capture image snapshot for all stories with `snapshot` tag,
// for both light and dark themes
createVisConfig(/* options */).presets.theme({
light() { document.body.classList.remove('dark') },
dark() { document.body.classList.add('dark') },
})
On storybook, you need to register the beforeEach
hook in .storybook/preview.ts
.
// .storybook/preview.tsx
import { storybookPreviewVis } from 'storybook-addon-vis'
export default {
// ...
beforeEach: storybookPreviewVis.beforeEach
}
Usage - automatic snapshot
With the basic
preset, storybook-addon-vis automatically captures image snapshot for stories with snapshot
tag.
As with how tags work in storybook, you can add the tag globally, per story file, or per story.
// .storybook/preview.tsx
export default {
// Enable image snapshot for all stories
tags: ['snapshot']
}
// story.tsx
export default {
title: 'Button',
// Take image snapshot automatically for all stories in this file
tags: ['snapshot']
}
export const MyStory = {
// Take image snapshot automatically for this story
tags: ['snapshot'],
// ...
}
You can disable snapshot capturing with the !snapshot
tag,
much like !test
.
export default {
title: 'Button',
// Enable image snapshot for all stories in this file
tags: ['snapshot']
}
export const MyStory = {
// Disable image snapshot for this story
tags: ['!snapshot'],
// ...
}
You can provide options to the toMatchImageSnapshot
matcher using parameters.
import { defineSnapshotParam } from 'storybook-addon-vis'
export const MyStory = {
parameters: defineSnapshotParam({
failureThreshold: 70,
})
// ...
}
Usage - manual snapshot
Besides automatic snapshot, you can capture image snapshot manually.
import { expect } from '@storybook/test'
// `page` and the like are proxies of `@vitest/browser/context` to work within storybook
import { page } from 'storybook-addon-vis'
export const PageSnapshot = {
// typically you want to disable automatic snapshot when using manual snapshot
tags: ['!snapshot'],
// ...
async play() {
await expect(page.imageSnapshot()).toMatchImageSnapshot()
}
}
export const ElementSnapshot = {
// typically you want to disable automatic snapshot when using manual snapshot
tags: ['!snapshot'],
// ...
async play({ canvas }) {
const element = await canvas.getByTestid('subject')
await expect(page.imageSnapshot({ element })).toMatchImageSnapshot()
}
}
Snapshot folder
By default, the snapshots are stored under the __vis__
folder at the root of the project:
v __vis__
˃ __diff_output__ # where the diff images are stored
˃ __result__ # where the resulting snapshot of the current run are stored
˃ darwin # snapshot generated on macos by CI
˃ linux # snapshot generated on linux by CI
v local # snapshot generated on local machine
v button.stories.tsx
snapshot-1.png
snapshot-2.png
v src
button.stories.tsx
You can change the snapshot folder by providing the snapshotDir
option to the createVisConfig
function.
import { createVisConfig } from 'storybook-addon-vis/vitest-setup'
createVisConfig({
snapshotRootDir: 'path/to/snapshot'
})
Typically, you place your test files either in a dedicated tests
folder or in the src
folder along with your source code.
By default, storybook-addon-vis removes that folder to reduces nesting.
If you place your test files in multiple folders,
such as in both tests
and src
folders,
you can use customizeSnapshotSubpath
to customize the snapshot sub-path to avoid conflicts.
import { createVisConfig } from 'storybook-addon-vis/vitest-setup'
createVisConfig({
// keep the folder structure
customizeSnapshotSubpath: (subpath) => subpath
})
With the above configuration, the snapshot folder structure will look like this:
v __vis__
> # ...
v local # snapshot generated on local machine
v examples
v button.stories.tsx
snapshot-1.png
snapshot-2.png
v src
v button.stories.tsx
snapshot-1.png
snapshot-2.png
v tests
v button.stories.tsx
snapshot-1.png
snapshot-2.png
v examples
button.stories.tsx
v src
button.stories.tsx
v tests
button.stories.tsx
Ignore snapshot folders
Some snapshot folders should be ignored by git.
With the default snapshot folder structure, you should add the following to your .gitignore
:
# .gitignore
**/__vis__/__diff_output__
**/__vis__/__results__
**/__vis__/local
Troubleshooting
Internal server error: Failed to resolve import "pathe"
This is likely a compatibility issue with pnpm
and vite
in monorepo.
To work around this, you can add shamefully-hoist
to your .npmrc
:
# .npmrc
shamefully-hoist=true