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https://github.com/percy/percy-storybook

Percy's Storybook SDK.
https://github.com/percy/percy-storybook

component component-visual-testing percy percy-sdk percy-storybook storybook testing visual-testing

Last synced: 11 days ago
JSON representation

Percy's Storybook SDK.

Host: GitHub
URL: https://github.com/percy/percy-storybook
Owner: percy
License: mit
Created: 2017-08-27T02:41:27.000Z (about 7 years ago)
Default Branch: master
Last Pushed: 2024-10-07T08:25:21.000Z (about 1 month ago)
Last Synced: 2024-10-12T00:32:46.978Z (27 days ago)
Topics: component, component-visual-testing, percy, percy-sdk, percy-storybook, storybook, testing, visual-testing
Language: JavaScript
Homepage: https://docs.percy.io/docs/storybook
Size: 10.1 MB
Stars: 149
Watchers: 12
Forks: 45
Open Issues: 15
Metadata Files:
- Readme: README.md
- License: LICENSE
- Codeowners: CODEOWNERS

Awesome Lists containing this project

README

# @percy/storybook
[![Version](https://img.shields.io/npm/v/@percy/storybook.svg)](https://npmjs.org/package/@percy/storybook)
![Test](https://github.com/percy/percy-storybook/workflows/Test/badge.svg)

## Visual Testing with Percy

[Percy](https://percy.io?utm_source=storybook&utm_medium=partnered&utm_campaign=documentation) is an all-in-one visual testing and review platform. It captures screenshots, compares them against the baseline, and highlights visual changes. With increased visual coverage, teams can deploy code changes with confidence with every commit.

[Storybook](https://storybook.js.org) supports cross-browser visual testing natively using Percy. You can use Percy for visual testing of web applications on desktop and mobile browsers.

Sign up [here](https://www.browserstack.com/users/sign_in?utm_source=storybook&utm_medium=partnered&utm_campaign=documentation) to get started with Percy for free.

The benefits of utilizing Percy for visual testing include the following:

- Consistency: Promotes consistent user experience by identifying visual discrepancies early in the development process.
- Efficiency: Improves efficiency by reducing the time and effort required to manually spot visual regressions.
- Integrations: Percy integrates with popular tools and services like GitHub, GitLab, Bitbucket, and more.
- Collaboration: Improves collaboration between developers, designers, and QA teams by providing a visual representation of changes.
- Prevent regression: Prevents you from experiencing unintended visual regressions.

## How does Percy work?

Percy compares new snapshots against relevant baselines to detect visual changes. Percy manages baseline selection across branches so your tests are always relevant. If visual changes are detected, Percy highlights and groups the resulting diffs for you to review.

## Run your first build with percy
[Percy’s sample build tutorial for Storybook.](https://www.browserstack.com/docs/percy/sample-build/storybook?utm_source=storybook&utm_medium=partnered&utm_campaign=documentation)

## Installation

``` session
$ npm install --save-dev @percy/cli @percy/storybook
```

## Usage

Before running the following commands, make sure your project's PERCY_TOKEN
is properly configured.

``` sh
# Unix
$ export PERCY_TOKEN=""

# Windows
$ set PERCY_TOKEN=""

# Powershell
$ $Env:PERCY_TOKEN=""
```

With a static Storybook build:

``` sh
$ percy storybook ./storybook-build
```

With a local or live Storybook URL:

``` sh
$ percy storybook http://localhost:9009
$ percy storybook https://storybook.foobar.com
```

Automatically run `start-storybook`:

``` sh
$ percy storybook:start --port=9009 --static-dir=./public
```

## Commands:

* [`percy storybook`](#percy-storybook)
* [`percy storybook:start`](#percy-storybookstart)

### `percy storybook`

Snapshot static or hosted Storybook stories

```
Usage:
$ percy storybook [options]

Arguments:
url|directory Storybook url or build output directory

Subcommands:
storybook:start [options] Run start-storybook to snapshot stories
help [command] Display command help

Options:
-i, --include Pattern matching story names to include in snapshots
-e, --exclude Pattern matching story names to exclude from snapshots
--shard-count Number of shards to split snapshots into
--shard-size Size of each shard to split snapshots into
--shard-index Index of the shard to take snapshots of
--partial Marks the build as a partial build

Percy options:
-c, --config Config file path
-d, --dry-run Print snapshot names only
-h, --allowed-hostname Allowed hostnames to capture in asset discovery
--disallowed-hostname Disallowed hostnames to abort in asset discovery
-t, --network-idle-timeout Asset discovery network idle timeout
--disable-cache Disable asset discovery caches
--debug Debug asset discovery and do not upload snapshots

Global options:
-v, --verbose Log everything
-q, --quiet Log errors only
-s, --silent Log nothing
--help Display command help

Examples:
$ percy storybook ./build
$ percy storybook http://localhost:9000/
```

### `percy storybook:start`

Run start-storybook to snapshot stories

```
Usage:
$ percy storybook:start [options]

Global options:
-v, --verbose Log everything
-q, --quiet Log errors only
-s, --silent Log nothing
--help Display command help

Examples:
$ percy storybook:start
$ percy storybook:start --port 9000
$ percy storybook:start --static-dir public
```

## Configuration

[Storybook parameters](https://storybook.js.org/docs/react/writing-stories/parameters) are a set of static,
named metadata about a story, used to control the behavior of Storybook features and addons. The `percy`
parameter can be provided to add per-snapshot configuration options to a story or set of stories.

``` javascript
// individual stories
MyStory.parameters = {
percy: { ... }
};
```
``` javascript
// .storybook/preview.js
export const parameters = {
percy: { ... }
};
```

The following `percy` Storybook parameters are accepted in addition to [common per-snapshot
options](https://www.browserstack.com/docs/percy/take-percy-snapshots/overview#per-snapshot-configuration?utm_source=storybook&utm_medium=partnered&utm_campaign=documentation):

- **skip** - Boolean indicating whether or not to skip this story.
- **name** - Snapshot name. (default: `${story.kind}: ${story.name}`)
- **args** - [Story args](https://storybook.js.org/docs/react/writing-stories/args) to use when
taking the snapshot.
- **globals** - [Story
globals](https://storybook.js.org/docs/react/essentials/toolbars-and-globals#globals) to use when
taking the snapshot.
- **queryParams** - Query parameters to use when snapshotting.
- **waitForTimeout** - Wait for a timeout before taking the snapshot.
- **waitForSelector** - Wait for a selector to exist before taking the snapshot.
- **include** - An array of regex patterns matching story names to only include for snapshotting.
- **exclude** - An array of regex patterns matching story names to always exclude from snapshotting.
- **additionalSnapshots** - An array of additional snapshots to take of this story.
- **prefix** - A prefix added to this additional snapshot's name.
- **suffix** - A suffix added to this additional snapshot's name.
- **name** - Snapshot name. Replaces the inherited name.
- **args** - Additional story args for this additional snapshot.
- **globals** - Additional story globals for this additional snapshot.
- **queryParams** - Additional query parameters for this additional snapshot.
- **include** - Only apply the additional snapshot to matching stories.
- **exclude** - Do not apply the additional snapshot to matching stories.

Click to see an example story configuration

``` javascript
MyStory.parameters = {
percy: {
name: 'My snapshot',
additionalSnapshots: [
{ prefix: '[Dark mode] ', args: { colorScheme: 'dark' } },
{ suffix: ' with a search', queryParams: { search: 'foobar' } }
]
}
};
```

With this example, 3 snapshots will be taken of this story with args and query params appended
to the URL of each snapshot:

``` sh
# --dry-run will log snapshots without creating a new build
# --verbose will show debug logs, including the snapshot url
$ percy storybook --dry-run --verbose ./example-storybook
# ...
[percy] Snapshot found: My snapshot
[percy] -> url: [...]?id=component--my-story
[percy] Snapshot found: [Dark mode] My snapshot
[percy] -> url: [...]?id=component--my-story&args=colorScheme:dark
[percy] Snapshot found: My snapshot with a search
[percy] -> url: [...]?id=component--my-story&search=foobar
```

## Percy config file options

In addition to [common Percy config file options](https://www.browserstack.com/docs/percy/take-percy-snapshots/overview),
this SDK also adds the following Storybook specific options:

``` yaml
# .percy.yml
version: 2
storybook:
args: {}
globals: {}
queryParams: {}
waitForTimeout: 0
waitForSelector: ''
additionalSnapshots: []
include: []
exclude: []
```

See the [configuration options above](#configuration) for details about each accepted config file
option (**note**: the `skip` and `name` parameters are _not_ accepted as Percy config file options).

## Upgrading

Prior versions of the Storybook SDK were drastically different than the current version. The
command, it's arguments, and how the SDK works internally have changed completely. Using the old
command with new versions will now result in an error message. The new command is now integrated into
[`@percy/cli`](https://github.com/percy/cli) as a plugin.

To use new versions of this SDK, you will have to also install the CLI with the SDK:

``` sh
$ npm install --save-dev @percy/cli @percy/storybook
```

Since both the command and arguments have changed, you'll need to replace your existing usage with
the [new usage described above](#usage). For some projects, this may require setting additional
[configuration options](#configuration). See the list of breaking changes below for details.

### Breaking changes

Most importantly, the command itself has changed and all previous arguments are no longer accepted.

- The `percy-storybook` command has been replaced with a [`percy` CLI](https://github.com/percy/cli)
subcommand, `percy storybook`.

- The previous `--build_dir` flag is now a command argument and there is no default build directory. If
you relied on the default, it must now be explicitly provided.

``` sh
# before
$ percy-storybook
# after
$ percy storybook ./storybook-static

# before
$ percy-storybook --build_dir ./build
# after
$ percy storybook ./build
```

- The `--widths` flag is no longer accepted. Widths can be set using the respective `widths`
[Percy config file `snapshot` option](https://www.browserstack.com/docs/percy/take-percy-snapshots/overview#snapshot) or
`percy` Storybook parameter.

- The `--minimum_height` flag is no longer accepted and therefore no longer defaults to
800px. The default minimum height shared by all SDKs is 1024px. The minimum height can be
set using the respective `min-height` [Percy config file `snapshot`
option](https://www.browserstack.com/docs/percy/take-percy-snapshots/overview#snapshot) or `percy` Storybook parameter.

- The `--debug` flag is now `--verbose`, inherited from the CLI.

- The `--output-format` flag is no longer accepted and has no alternative. If you relied on this
flag, please open an issue.

- The `--rtl` and `--rtl_regex` flags are no longer accepted. The `--rtl` flag duplicated stories
and set the `direction=rtl` query parameter for the duplicate's URL. The `--rtl_regex` flag was
used to determine when to create this RTL duplicate story.

Click here to see how to replicate the old behaviour with new configuration
options

``` js
// .storybook/preview.js

export const parameters = {
percy: {
// tell percy to take an additional RTL snapshot for matching stories
additionalSnapshots: [{
suffix: ' [RTL]',
queryParams: { direction: 'rtl' },
include: ['^FormElement: .*']
}]
}
};
```

#### Performance

The old SDK did not take DOM snapshots or perform asset discovery, as all other modern Percy SDKs
do. This sometimes resulted in flakey snapshots or snapshots with missing assets. However, DOM
snapshots and asset discovery add an overhead cost of performance. Where the old SDK was very quick
to simply upload the local build directory, the new SDK can be a little slower while it is capturing
the real DOM and relevant assets of each story.

#### Unexpected diffs

Because the old SDK did not take DOM snapshots, JavaScript had to be enabled in our rendering
environment for Storybook to properly load. This is in contrast to all of our other SDKs, where
JavaScript is disabled by default to prevent flakey diffs caused by animations or other JavaScript
running on the page. With the new SDK and real DOM snapshots, JS is disabled by default. If you
upgrade and experience diffs due to the lack of JavaScript, it can be re-enabled using the matching
Percy config file or per-snapshot option, [`enableJavaScript`](https://www.browserstack.com/docs/percy/take-percy-snapshots/overview#snapshot).

## Development
- Current package.json and yarn.lock install storybook v7 as devDependency and hence require node 16 for development.
- There are separate package.json and config files for storybook v6, for testing purposes. Please check `prepare-storybook-v6-tests.sh` file for more details around changes for storybook v6 testing.