By Makoto Ueki — We need to clarify the accessibility requirements that the content should ensure in the requirements definition phase. Then we design and develop the content following the requirements. Once the content is developed, we need to verify that it meets the requirements set forth in the final quality assurance phase.
There are many ways to verify that the requirements are met, and testing tools are essential for streamlining the process. However, when testing the accessibility of content, there is something you should know before using a testing tool.
It is a common theory that only 20%–30% of all web accessibility cases can be checked with a testing tool.
Let’s take one specific example of a case that cannot be determined by testing tools alone. Web accessibility guidelines include the criterion, “Provide alternative text that conveys equivalent information for an image.” A testing tool can automatically check for the following:
- Look for an
<img>element in the HTML code. - Check if the
<img>element has analtattribute. - Check if there is some string as the value of the
altattribute.
However, you must check the alternative text described as the alt attribute value to determine if it is appropriate as the text alternative for the image. No testing tool can reliably do this part.
Even if it is the same image, the appropriate alternative text may vary depend‑ ing on the preceding and following content and context. For this reason, you should also check where the image you are checking is used on the web page.
Unfortunately, technology at this time does not allow us to automatically determine if the alternative text wording is appropriate.
Another example is the criterion, “Make information and relationships on the web page machine readable.” An example is headings—headings on a web page should be properly marked up with HTML heading elements. What a testing tool can do is check for the following:
- Find the
<h1>to<h6>elements in the HTML code. - Check for skipped heading levels.
However, where on the web page the headings to be checked are located must first be visually confirmed. In other words, the checking tool cannot mechanically and automatically find the target to be checked in the first place.
These are criteria that seem relatively easy to check with a testing tool. But you can see that, even so, not everything can be automated. Most of the work to check the accessibility of a web page requires human visual inspection, keyboarding, and assistive technology to make sure it meets the requirements.
Therefore, even if a check tool gives a score of more than 90 out of 100, you’ll fnd many issues while you are performing a complete human check.
Testing tools should be used proactively as a tool to improve your work efficiency. However, it is important to keep in mind that the testing tool can only improve the efficiency of a limited part of the entire process.
From Horton, S., & Sloan, D. (2024). What Every Engineer Should Know About Digital Accessibility. CRC Press, Boca Raton, Florida.
Know About Accessibility 