Accessibility Testing Requirements – Perceivable – Distinguishable

Posted by Albert Gareev on Oct 02, 2014 | Categories: AccessibilityReviews

In the series of reviews I’m looking at WCAG level A / AA (Web Content Accessibility Guidelines) requirements from testing perspective.

Common Definitions

Human Testing

  • Brief – “You know as you see it” – quick scanning is sufficient to check and make a judgment. This does not include effort of logging defects.
  • Detailed – Either interaction (execution of tests) with the functionality is necessary or detailed review/analysis must be done in order to verify a requirement.

Tool-Assisted Checking

  • Not Available – Tools cannot help in checking for the specified requirement or they help very insignificantly.
  • Partial – Tools provide significant help in checking for the specified requirement, either by saving time in parsing content source or through visualization. Human does the verification and judgment.
  • Full – Tools capable of locating and verifying the specified requirement. Brief review of checking results is sufficient to make a judgment.

Perceivable – Distinguishable

Make it easier for users to see and hear content including separating foreground from background.

Tools for color picking and analysis help to identify contrast levels, as well as represent content in alternate colors (mono-chromatic, di-chromatic, three-chromatic) as it would be seen by people with color with deficiencies.

Application-specific GUI design requirements must be set to create compliant and consistent distinguishable content.

QA can perform testing to certain extent for color and sound specific requirements. QA can perform testing of assistive functionalities.

For the application testing, creating a mock of all color/contrast samples from the app’s CSS would greatly reduce scope of testing and increase efficiency.


Color is not used as the sole method of conveying content or distinguishing visual elements.

Human Testing – Brief

Tool-Assisted Checking – Not available

Tools don’t verify that, brief review by a human is required.

Colour – links

Color alone is not used to distinguish links from surrounding text unless the luminance contrast between the link and the surrounding text is at least 3:1 and an additional differentiation (e.g., it becomes underlined) is provided when the link is hovered over or receives focus.

Human Testing – Brief

Tool-Assisted Checking – Partial

Special tools for color picking and analysis should be employed for verification. Testers can review results. Attention should be paid for consistency of color pattern used (because tools don’t check that), and gradient (if used).

For a framework-based GUI, sampling of each class of links is sufficient, no need to verify every single page.

Audio Control

A mechanism is provided to stop, pause, mute, or adjust volume for audio that automatically plays on a page for more than 3 seconds.

Human Testing – Special

Tool-Assisted Checking – Not available

Testers need to check for presence of the mechanism and test its functionality.

Contrast ratio

Text and images of text have a contrast ratio of at least 4.5:1.

Human Testing – Brief

Tool-Assisted Checking – Full

Special tools for color picking and analysis should be employed for verification. Testers can review results.

Resize text

The page is readable and functional when the text size is increased up to 200%.

Human Testing – Detailed

Tool-Assisted Checking – Not available

Brief assessment for readability. More detailed effort to verify functional aspects. This can be combined with functional testing. 

GUI Automation tools will have trouble with that – Selenium goes beneath the visual, QTP and TestComplete support visual at 100% size.

Images of text

If the same visual presentation can be made using text alone, an image is not used to present that text.

Human Testing – Brief

Tool-Assisted Checking – Not available

This can be done at design stages, while reviewing UI mock-ups.



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Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported
This work by Albert Gareev is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported.