@percy/cli-snapshot

What is @percy/cli-snapshot?

@percy/cli-snapshot is a command-line tool for capturing visual snapshots of web pages and components. It integrates with Percy, a visual testing and review platform, to help developers catch visual regressions in their web applications.

What are @percy/cli-snapshot's main functionalities?

Capture a snapshot of a single URL

This command captures a visual snapshot of the specified URL and uploads it to Percy for visual comparison.

npx @percy/cli-snapshot http://example.com

Capture snapshots from a list of URLs

This command reads a list of URLs from a file (urls.txt) and captures visual snapshots for each URL, uploading them to Percy.

npx @percy/cli-snapshot urls.txt

Capture snapshots with custom widths

This command captures visual snapshots of the specified URL at different viewport widths (375px, 768px, and 1280px) and uploads them to Percy.

npx @percy/cli-snapshot http://example.com --widths=375,768,1280

Capture snapshots with custom CSS

This command captures a visual snapshot of the specified URL with custom CSS applied, and uploads it to Percy.

npx @percy/cli-snapshot http://example.com --css='body { background-color: red; }'

Capture snapshots with authentication

This command captures a visual snapshot of a URL that requires basic authentication, using the provided username and password, and uploads it to Percy.

npx @percy/cli-snapshot http://example.com --auth=username:password

Other packages similar to @percy/cli-snapshot

puppeteer

Puppeteer is a Node library that provides a high-level API to control Chrome or Chromium over the DevTools Protocol. It can be used for taking screenshots, generating PDFs, and automating web interactions. Unlike @percy/cli-snapshot, Puppeteer does not integrate directly with a visual testing platform like Percy.

cypress

Cypress is a JavaScript end-to-end testing framework that allows developers to write tests for web applications. It includes features for taking screenshots and recording videos of tests. While Cypress focuses on functional testing, it can be extended with plugins to perform visual testing, but it does not natively integrate with Percy like @percy/cli-snapshot.

webdriverio

WebdriverIO is a test automation framework that allows you to run tests based on the WebDriver protocol and Appium. It supports taking screenshots and can be integrated with visual regression testing tools. However, it does not provide the same out-of-the-box integration with Percy as @percy/cli-snapshot.

README

@percy/cli-snapshot

Snapshot a list or static directory of web pages.

Commands

• percy snapshot

percy snapshot

Snapshot a static directory, snapshots file, or sitemap URL

Usage:
  $ percy snapshot [options] <dir|file|sitemap>

Arguments:
  dir|file|sitemap                   Static directory, snapshots file, or sitemap url

Options:
  -b, --base-url <string>            The base url pages are hosted at when snapshotting
  --include <pattern>                One or more globs/patterns matching snapshots to include
  --exclude <pattern>                One or more globs/patterns matching snapshots to exclude

Static options:
  --clean-urls                       Rewrite static index and filepath URLs to be clean

Percy options:
  -c, --config <file>                Config file path
  -d, --dry-run                      Print snapshot names only
  -h, --allowed-hostname <hostname>  Allowed hostnames to capture in asset discovery
  --disallowed-hostname <hostname>   Disallowed hostnames to abort in asset discovery
  -t, --network-idle-timeout <ms>    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 snapshot ./public
  $ percy snapshot snapshots.yml
  $ percy snapshot https://percy.io/sitemap.xml

Usage

Snapshot Lists

When providing a file containing a list of snapshots, the file must be YAML, JSON, or a JS file exporting a list of pages. Each snapshot must contain at least a url that can be navigated to using a browser.

snapshots.yml:

- http://localhost:8080
- http://localhost:8080/two

Snapshotting snapshots.yml:

$ percy snapshot snapshots.yml
[percy] Percy has started!
[percy] Snapshot taken: /
[percy] Snapshot taken: /two
[percy] Finalized build #1: https://percy.io/org/project/123

Snapshot Options

A name can be provided which will override the default snapshot name generated from the url path. The options waitForTimeout and waitForSelector can also be provided to wait for a timeout or selector respectively before taking the snapshot.

snapshots.json:

[{
  "name": "Snapshot one",
  "url": "http://localhost:8080",
  "waitForTimeout": 1000
}, {
  "name": "Snapshot two",
  "url": "http://localhost:8080/two",
  "waitForSelector": ".some-element"
}]

Snapshotting snapshots.json:

$ percy snapshot snapshots.json
[percy] Percy has started!
[percy] Snapshot taken: Snapshot one
[percy] Snapshot taken: Snapshot two
[percy] Finalized build #1: https://percy.io/org/project/123

For more advanced use cases, an execute function and additionalSnapshots may be specified for each snapshot to execute JavaScript within the page execution context before subsequent snapshots are taken.

Note: All options are also accepted by other file formats. For execute however, a string containing a function body can be provided when the file format prevents normal functions.

snapshots.js:

module.exports = [{
  name: 'My form',
  url: 'http://localhost:8080/form',
  waitForSelector: '.form-loaded',
  execute() {
    document.querySelector('.name').value = 'Name Namerson';
    document.querySelector('.email').value = '[e-mail]';
  },
  additionalSnapshots: [{
    suffix: ' - submitting',
    execute() {
      document.querySelector('.submit').click();
    }
  }, {
    suffix: ' - after submit',
    waitForSelector: '.form-submitted'
  }]
}]

Snapshotting snapshots.js:

$ percy snapshot snapshots.js
[percy] Percy has started!
[percy] Snapshot taken: My form
[percy] Snapshot taken: My form - submitting
[percy] Snapshot taken: My form - after submit
[percy] Finalized build #1: https://percy.io/org/project/123

JavaScript files may also export sync or async functions that return a list of pages to snapshot.

module.exports = async () => {
  let urls = await getSnapshotUrls()
  return urls.map(url => ({ name: url, url }))
}

Advanced List Options

Instead of an array of snapshots, list files can also contain an object that defines additional top-level options along with a snapshots option containing the array of snapshots. This allows dynamically filtering lists with include/exclude options, and enables utilizing features such as YAML anchors and references.

Example snapshots.yml

base-url: https://example.com
exclude:
  - /page/(\d+)

references:
  dismiss-cookie-banner: &dismiss-cookie-banner |
    document.querySelector('.cookie-banner .dismiss').click();

snapshots:
  - url: /foo
    execute: *dismiss-cookie-banner
  - url: /foo
    name: "/foo - with cookie banner"
  - url: /bar
    execute: *dismiss-cookie-banner

Static Directory

When providing a static directory, it will be served locally and pages matching the files argument (and excluding the ignore argument) will be navigated to and snapshotted.

$ percy snapshot ./public
[percy] Percy has started!
[percy] Snapshot taken: /index.html
[percy] Snapshot taken: /about.html
[percy] Snapshot taken: /contact.html
[percy] Finalized build #1: https://percy.io/org/project/123

Static Options

For snapshotting static directories, the following Percy config file options are also accepted:

# .percy.yml
version: 2
static:
  base-url: /
  clean-urls: false
  include: **/*.html
  exclude: []
  rewrites: {}
  options: []

• base-url - The base URL path the static site should be served under.
• clean-urls - When true, rewrite index and filepath URLs to be clean.

• include/exclude - A predicate or an array of predicates matching snapshots to include/exclude.

  A predicate can be a string glob or pattern, a regular expression, or a function that accepts a snapshot object and returns true or false if the snapshot is considered matching or not.

  // .percy.js
  module.exports = {
    version: 2,
    static: {
      include: [
        'blog/**/*.html',          // glob
        'pages/page-(?!10).html$', // pattern
        /about-(.+)\.html/i        // regexp
      ],
      exclude: [
        // function that returns true when matching
        ({ name }) => DISALLOWED.includes(name)
      ]
    }
  };
  

• rewrites - An object containing source-destination pairs for rewriting URLs.

  Paths for resources can sometimes be expected to be in a certain format that may not be covered by the clean-urls option. For such paths, rewrites can map a short, clean, or pretty path to a specific resource. Paths are matched using path-to-regexp.

  # .percy.yml
  version: 2
  static:
    base-url: /blog
    rewrites:
      /:year/:month/:title: /posts/:year-:month--:title.html
      /:year/:month: /posts/index-:year-:month.html
      /:year: /posts/index-:year.html
  

• options - An array of per-snapshot options.

  Just like page listing options, static snapshots may also contain per-snapshot configuration options. However, since pages are matched against the files option, so are per-snapshot configuration options via an array of options. If multiple options match a snapshot, they will be merged with previously matched options.

  # .percy.yml
  version: 2
  static:
    options:
    - files: /foo-bar.html
      waitForSelector: .is-ready
      execute: |
        document.querySelector('.button').click()
  

Sitemap URL

When providing a sitemap URL, the document must be an XML document. For sitemap URLs the --include and --exclude flags can be used to filter snapshots. With a Percy config file, the options option is also accepted.

Tip: Sitemaps can contain a lot of URLs, so its best to always start with the --dry-run flag while fine tuning the include and exclude options.

$ percy snapshot https://percy.io/sitemap.xml --dry-run
[percy] Found 10 snapshots
[percy] Snapshot found: /
[percy] Snapshot found: /changelog
[percy] Snapshot found: /customers
[percy] Snapshot found: /enterprise
[percy] Snapshot found: /features
[percy] Snapshot found: /how-it-works
[percy] Snapshot found: /integrations
[percy] Snapshot found: /pricing
[percy] Snapshot found: /security
[percy] Snapshot found: /visual-testing

Sitemap Options

For snapshotting sitemaps, the following Percy config file options are accepted:

# .percy.yml
version: 2
static:
  include: **/*.html
  exclude: []
  options: []

See the corresponding static options for details on includes, excludes, and options options.