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Migration Guide

Pa11y's API changes between major versions. This is a guide to help you make the switch when this happens.

Table Of Contents

Migrating from 4.0 to 5.0

PhantomJS to Headless Chrome

Pa11y 5.0 switches from PhantomJS to Headless Chrome. This allows us to use more modern JavaScript APIs and make Pa11y testing more stable.

Node.js Support

Pa11y 5.0 only supports Node.js v8.0.0 and higher, you'll need to upgrade to be able to use the latest versions of Pa11y.

Warnings and Notices

Pa11y 5.0 ignores warnings and notices by default, as these are not usually actionable or useful in automated testing.

You can force Pa11y to include warnings and notices again by using the --include-notices and --include-warnings command-line flags, or the includeNotices and includeWarnings options.

Command-Line Interface

The command-line interface in 5.0 is similar to 4.0, but there are a few key changes.

  • The --verify-page flag has been removed, as page verification can be achieved with screen-shots or observing the debug output
  • The --htmlcs flag has been removed, you can no longer configure the version of HTML CodeSniffer that Pa11y uses. An alternative would be to fork Pa11y for your individual use and replace HTML CodeSniffer, we'll be reviewing how we allow this again in future
  • The --port flag has been removed, as this is not required to run multiple Headless Chrome instances

JavaScript Interface

Pa11y is now completely Promise-based, and uses async/await internally. This means the API has changed significantly.

You no longer need to create a separate test function, now Pa11y is just one function: pa11y(url, options). See the README for more information.

Reporters

The following reporters have been removed from Pa11y:

  • html: The HTML reporter has moved outside of Pa11y, please install using npm install pa11y-reporter-html
  • markdown: The Markdown reporter has been removed. We may introduce it as a separate module at a later date
  • tsv: The TSV reporter has moved outside of Pa11y, please install using npm install pa11y-reporter-tsv

Additionally the reporter interface has had an overhaul, and reporters that work for Pa11y 4.0 won't work for 5.0. See the README for more information on the API changes.

Configuration

Configuration options have had an update between 4.0 and 5.0:

  • The allowedStandards option has been removed. This can still be set by manually adding entries to pa11y.allowedStandards
  • The beforeScript option has been removed in favour of using actions (if the existing actions don't meet your needs, please let us know)
  • The htmlcs option has been removed, you can no longer configure the version of HTML CodeSniffer that Pa11y uses. An alternative would be to fork Pa11y for your individual use and replace HTML CodeSniffer, we'll be reviewing how we allow this again in future
  • The page option has been removed, as this was specific to PhantomJS. You can set the following options to achieve the same results:
    • page.headers can now be set with a new headers option
    • page.settings.data can now be set with a new postData option
    • page.settings.operation can now be set with a new method option
    • page.settings.userAgent can now be set with a new userAgent option
    • page.viewport can now be set with a new viewport option
  • The phantom option has been removed, as this was specific to PhantomJS
  • The verifyPage option has been removed, as page verification can be achieved with screen-shots or by inspecting the documentTitle property of the results

Miscellaneous Changes

  • The default viewport dimensions for Pa11y have been changed from 1024x768 to 1280x1024
  • The wait-for-element-state action no longer has a maximum number of retries – it will retry until Pa11y times out
  • The "multiple-concurrent" example has been removed in favour of a single "multiple" example

Migrating from 3.0 to 4.0

Node.js Support

The only breaking change in Pa11y 4.0 is that Node.js 0.12 is no longer supported. We'll be using newer ES6 features in upcoming releases which will not work in this older Node.js version.

Migrating from 2.0 to 3.0

API Overhaul

The Pa11y JavaScript API has been overhauled completely. It would be best to refer to the usage guide in the README as your code will need refactoring.

Randomized Ports

The phantom.port option no longer has a default. If a port is not specified, then Pa11y will bind to an available port. This allows for easier running of tests in parallel, as PhantomJS instances will no longer conflict with each other.

Node.js Support

Node.js 0.10 is no longer officially supported, Pa11y is unlikely to continue to work with this version going forward.

Migrating from 1.0 to 2.0

Command-Line Interface

The command-line interface in 2.0 is similar to 1.0, but there are a few key changes.

  • The console reporter has been renamed to cli and has a different output format
  • The csv reporter now includes the message context and selector
  • The json reporter now outputs an array which matches the new output format. You can use the Pa11y JSON 1.0 reporter to output 1.0-style JSON
  • Reporters no longer handle the way Pa11y exits, this is controlled through the new --level flag
  • Custom reporters now have a different API, see the README for more information
  • The file specified by the --config flag now expects JSON in a different format. See configuration
  • The --htmlcs flag shorthand has been changed to -H
  • The --useragent flag has been removed, this is now managed through the config file
  • The --viewport flag has been removed, this is now managed through the config file
  • The --strict flag has been removed, this is controlled through the new --level flag
  • HTML CodeSniffer is now loaded from a local file by default so tests can be run offline

JavaScript Interface

A two-step running process is now used over a single pa11y.sniff() function. This allows a single PhantomJS browser to run multiple tests, reducing memory usage and making Pa11y more useful to derivative tools. See the README for more information.

Output Format

Results in Pa11y 2.0 are no longer output as an object, instead only the results array is provided. It's up to your code (or reporter) to add totals etc. Also the result format has been changed:

// 1.0 result
{
  code: 'WCAG2AA.Principle2.Guideline2_4.2_4_2.H25.2',
  message: 'Check that the title element describes the document.',
  type: 'notice',
  html: '<title>Pa11y - Your automated accessib...</title>'
}

// 2.0 result
{
    code: 'WCAG2AA.Principle2.Guideline2_4.2_4_2.H25.2',
    context: '<title>Pa11y - Your automated accessib...</title>',
    message: 'Check that the title element describes the document.',
    selector: 'html > head > title',
    type: 'notice',
    typeCode: 3
}

Configuration

Configuration options have had a big overhaul between 1.0 and 2.0:

  • The url option has been removed. See JavaScript Interface for more information
  • The config option has been removed. Cookies are now set as in the page.headers option. Ignored rules are now set in a new ignore option
  • The ignore option now accepts message types (error, warning, notice) as well as codes
  • The useragent option has been removed, it can now be set in the page.headers option
  • The port option has been removed, it can now be set in the phantom.port option
  • The viewport option has been removed, it can now be set in the page.viewport option
  • The debug option has been removed, debugging is now handled by the log.debug option which expects a function

Contributing/Testing

Pa11y 2.0 uses Make over Grunt as a build tool. For Windows users, all of the Make targets should be runnable individually by copying commands from the Makefile and running within a terminal.