Accessibility Auditing - CDCgov/prime-simplereport GitHub Wiki

Using Automated Methods to keep SimpleReport Accessible

Accessibility is a primary concern in keeping SimpleReport available and delightful to all users. SimpleReport uses a combination of methods to ensure the application satisfies accessibility requirements. These include:

  • Manual audits with a variety of tools
  • Lighthouse page testing
  • Automated user flow tests, utilizing cypress axe

✌️ Manual Audits

Manual audits are a good way to confirm that automated testing catches errors properly and to test accessibility implementation locally. This can be done with the official Axe toolkit from Deque, which can be run manually as a browser dev tools extension or utilized to run automated guided tests as well.

Other helpful browser extensions for local testing:

Quarterly Audits with Deque Axe Dev Tool

General Tips

  1. Depending on the page and functionality being tested, feel free to test against a lower environment or your local environment. (Just make sure you are on the latest and greatest of main.)

  2. Make sure you are logged in to your Enterprise Deque account. You should have been granted access after completing all the Deque courses.

Not logged in

Logged in

  1. If you want to test a section of the webpage, select the "Scan PART of my page" option. Otherwise, errors in parts of the site (e.g. header) that are repeated on every page will get flagged again.

"Scan PART of my page" option

Select area you wish to run audit on

  1. Ensure under Settings > Advanced > "Server settings" > "axe Server URL" is pointing to the cdc dequecloud url

  2. You can view all previously saved tests so when you go to "Save test" (which is required when running the "Guided Tests") provide a helpful title

💡 Lighthouse Testing

Background

Lighthouse is an open-source tool developed by google to improve the quality of web apps. While five categories can be audited with Lighthouse testing, SimpleReport utilizes only the accessibility and performance categories. Lighthouse audits run on a provided URL (or list of URLs) and return results for the specified page. The accessibility results do not seem as granular as Axe tests but offer an easy way to catch egregious regressions in the app. Currently, we run Lighthouse audits on every PR.

Note that Lighthouse provides two tools for running Lighthouse tests, lighthouse, which is a CLI tool, and lighthouse-ci (aka lhci), which is another CLI tool optimized for CI configuration. SimpleReport utilizes lighthouse-ci for testing in CI/CD pipelines. See SimpleReport's Github action and configuration for Lighthouse.

Resources

🔁 e2e Testing

Background

SimpleReport utilizes the cypress-axe and axe-core npm packages to configure accessibility testing in cypress e2e tests. The axe tests reliably catch errors and produce few to no false positives. These tests are run on each PR in the CI/CD pipeline and can also be run locally. See the Cypress wiki page.

To test the accessibility on a page, after visiting a page with cy.visit(), inject axe and check accessibility like so:

cy.injectAxe();
cy.checkA11y();

The Deque blog has a good blog post for setting up axe in cypress.

Though generally not recommended, it is possible to exclude components or set rules to ignore specific errors. For example, see the official GitHub repo docs and this helpful blog.

Gotchas - When adding accessibility checks in cypress, it's best to wait to call cy.checkA11y() until you confirm the page has loaded; otherwise, the check may fail in unexpected and incorrect ways. The checks are most reliable immediately after an assertion like .get or .contains that does not additionally do an action (like a .click) that changes the page.

Also worth noting, because cypress will retry a test if it fails, note that when it re-runs after an accessibility failure, the second run will likely fail for a different reason.

Resources

🔖 Other Resources

For the future... There are a variety of other ways to implement automated accessibility testing. This article outlines a few options for GitHub actions.