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Accessibility Scanning

Building a website or application that is easy accessible to everyone is not only an important of the user experience, but also a requirement of all federally funded projects. GSA provides a helpful Section 508 portal. Accessibility should not just be an afterthought! Start thinking about how to make your projects accessible before you begin any development.

While coding a site to be accessible is a responsibility for engineers, accessibility is not just a concern for engineering. Accessibility for Teams is a GSA-owned guide that gives explicit suggestions for the whole team product team can approach accessibility. It lists out ways to manually test your site, as well as giving automated testing guidance.

A more exhaustive list of elements and tools can be found at the 18F Accessibility Guide.

Recommended Tools

Pa11y With aXe-core Standard

Pa11y maintains a handful of open-source automated testing tools that scan your sites to check for accessibility problems. Their tools can be setup on your machine locally or remotely using a CI tool.

We are going to focus on Pa11y-ci, which is more geared towards use on projects in CI. (But can be run locally.)

Pa11y also maintains Pa11y that allows you to look at live sites or incorporate pa11y tests into an integration testing framework. (See below)

While Pa11y gives you the option of different test runners, we recommend using aXe-core.

aXe-core Standard

aXe-core is an open source accessibility testing engine; it includes a set of accessibility rules that Pa11y will test against. It is also possible to incorporate aXe-core directly into your integration tests as well.

Running Pa11y in CI

GitHub Actions On Every Pull Request

Thanks to Daniel Mundra and the folks at CivicActions Accessibility and their comprehensive documentation on setting up Pa11y-ci. All below code is taken from that blog post; read through for more details.

Their instructions are specific to Jekyll but can be leveraged for other types of projects.

  • Install pa11y locally

    $ npm i --save-dev pa11y-ci

  • Add pa11y-specific scripts to package.json

    "scripts": {
        "bundle exec jekyll serve --detach",
        "pa11y-ci --sitemap http://localhost:4000/sitemap.xml --sitemap-exclude \"/*.pdf\""

18F accessibility site’s .pallyci. $ touch .pa11yci

      "defaults": {
        "concurrency": 4,
        "standard": "WCAG2AA",
        "runners": ["axe"]
  • Create .github/workflows directories in the root of your project, and then a pa11y.yml file in workflows.
  $ mkdir -P .github/workflows
  $ touch .github/workflows/pa11y.yml

Create your Github Action workflow!

To see a pa11y.yml live in the wild, check out 18F Accessibility site’s pa11y.yml.

Circle CI Setup Instructions

If you want to run Pa11y-ci per pull request on your project:

  1. Create a bash file in your project home directory to tell it to run either on a circleci supported branch or your localhost

    if [[ -n $CIRCLE_BRANCH ]]; then
      echo "scanning site using sitemap from 18F/${CIRCLE_BRANCH}"
      pa11y-ci --sitemap${CIRCLE_BRANCH}/sitemap.xml
    echo "scanning site using localhost sitemap"
    pa11y-ci --sitemap http://localhost:4000/sitemap.xml
  2. Modify your circle.yml to add pa11y-ci

                - [Your-other-commands]
                - nvm install stable && nvm alias default stable
                - npm test
                - npm install -g pa11y-ci
           - bundle exec htmlproofer _site --disable-external --allow-hash-href --empty-alt-ignore --url-ignore
           - echo CIRCLE_BRANCH
           - echo
           - npm run --harmony accessibility-scan

Travis CI Setup Instructions(To Be Written)

Adding Pa11y To The Compliance Viewer(To Be Written)

Pa11y CLI

If you’d like to test a live website, whether or not you have accesss to the code, the Pa11y CLI can help!

The CLI requires Node.js 8+, which you can install with homebrew or nvm.

$ brew install node or $ nvm install node

Install the CLI globally on your machine:

$ npm install -g pa11y

and then you can run it against a live site.

$ pa11y

Welcome to Pa11y

> Running Pa11y on URL

No issues found!