Next steps: accessibility testing

[gabalafou]

Copied from comment on now closed issue:

• Summary of Axe accessibility issues #1428 (comment)_

---

Almost all of the Axe violations for our current set of test pages have been addressed. Our recent upgrade of Accessible-pygments fixed most of the remaining color contrast issues.

There are only two remaining color contrast issues:

• Notebook cell numbers (output via nbsphinx) do not have enough contrast, neither in light mode nor in dark mode.
• Xarray has some color contrast issues:
  • Fix some of these with Force light mode for notebook outputs #1812
  • For the others, write some special case style rules to override Xarray's own styles in the short-term,
  • Longer term, file an issue or pull request to fix upstream

The only other issue has to do with ipyleaflet. When that widget fails to load, it displays a SVG icon of a broken document, but that SVG icon does not have alt text. This is also something outside our control and we will need to file an issue or pull request upstream. In the meantime, I will add code to:

• Ignore the accessibility violation from the ipyleaflet error missing alt text

Future work

• Strategically add a few more of our docs pages to our set of test pages to scan with Axe-core
• Work with maintainers of nbsphinx, MyST-NB, ipywidgets, and other tools in the PyData ecosystem to improve their accessibility