The accessibility tester strikes again! In this article, we introduce another "blind spot" of automated accessibility testing tools: the bypass – and it’s not what you might think at first.

Related articles:

• https://magazine.joomla.org/all-issues/may-2025/blind-spots-of-accessibility-testing-tools-colour-contrast
• https://magazine.joomla.org/all-issues/june-2025/the-blind-spots-of-accessibility-testing-tools-alt-text

Bypass

One of the less known rules in WCAG 2.2 says: Provide a way to bypass blocks of content that are repeated on multiple Web pages. https://www.w3.org/WAI/WCAG21/Understanding/bypass-blocks

Testing is easy: Open a page and TAB. 

If you have activated the Joomla plugin skipto-navigation, the user will see a link which opens a drop down and can skip to sections in this page. 

Also a simple Button  which  leads to the main content is sufficient to fulfill the WCAG requirement.

The automatic testing tools which I am using for tests are not able to recognise violations of this rule. 

Only the IBM Accessibility Checker shows a warning and remembers the tester that this is important. 

More on the Blind Spots on alt texts: Background images

In this article we found: every test tool finds missing alt-text in images - but that's not quite correct! 
Background images which are imported via CSS or images which are injected via javascript after the DOM is loaded can have no alt texts and tools don’t care. 

With my favourite Tool: WAVE

The tool recognises a very bad contrast ratio. 

This is a false positive, as the text is white, the background is white. BUT the tool does not recognise the background image. 

The tool also gives a warning because the text has the same css definition as a <h1>. This too is a fals positive. 
The text has class=”h1” it is not a heading. 

But the missing alt-text was not recognised. The usage of background images must be restricted to really “decorative images”.

Here we have again two examples which show clearly that human tests are inevitable and we cannot rely on automatic tests only.