Accessibility Testing: Functional and Non-Functional Aspects

With most aspects of our lives moving online, ensuring digital accessibility is a strategic differentiator. According to the World Health Organization (WHO), over 1.3 billion people—roughly 16% of the global population—live with some form of disability. In the United States alone, one in four adults reports having a disability that affects their daily interactions, including how they navigate and use websites, mobile apps, and digital services.

Despite this, an overwhelming 95.9% of the top one million websites still fail to meet basic Web Content Accessibility Guidelines (WCAG) 2.1 AA standards as of early 2024. The consequences of neglecting accessibility extend beyond user frustration. In the U.S., the number of digital accessibility-related lawsuits filed under the Americans with Disabilities Act (ADA) has increased year-over-year, reaching nearly 5,000 cases in 2024 alone. Whether you’re a software developer or a business owner, these numbers should be a wake-up call.

Accessible design and development help expand market reach, improve customer experience, and reduce the risk of legal repercussions. But to achieve these outcomes, teams must move beyond surface-level checks and embrace both functional and non-functional accessibility testing.

In this article, we’ll explore both functional and non-functional aspects of accessibility testing, how they map to the broader QA process, and what best practices software teams should follow to integrate accessibility testing throughout the development lifecycle.

Functional accessibility testing

Functional accessibility testing focuses on how well users with disabilities can complete specific tasks within your software or application. It’s about validating that all interactive components—from navigation menus and form inputs to dynamic content and modals—are usable by people who rely on assistive technologies like screen readers, voice control systems, or keyboard-only navigation.

From a QA perspective, functional testing involves verifying that the core features of your application do not create barriers for users with visual, auditory, motor, or cognitive impairments. This testing is often conducted using a combination of automated tools and manual testing, the latter being essential for catching nuances that tools alone can miss.

Key areas of functional accessibility testing

1. Keyboard accessibility. Every interactive element, including buttons, dropdowns, sliders, and modals, should be operable using only the keyboard. QA testers should validate focus order, tab navigation, skip links, and the use of logical focus indicators. This is vital for users who cannot use a mouse due to motor impairments.
2. Screen reader compatibility. Testers should verify that screen readers (such as NVDA, JAWS, or VoiceOver) can correctly interpret content structure, announce roles and labels, and support navigation. This includes ensuring appropriate use of headings, ARIA attributes, and landmarks.
3. Form accessibility. All form fields should have descriptive labels and clear error messages. Visual cues like color should not be the only means of indicating input errors. Functional tests must ensure screen readers announce field instructions, errors, and required fields.
4. Image alt text. All informative images must have meaningful alt text. Decorative images should be marked appropriately so screen readers can skip them. This supports visually impaired users in understanding content that’s conveyed visually.
5. Accessible multimedia. Videos should include closed captions and audio descriptions where needed. Audio content should have transcripts available. Functional tests check if media controls are keyboard-accessible and screen-reader friendly.
6. Responsive behavior and zooming. Users should be able to zoom up to 200% without losing content or functionality. QA teams should test across breakpoints to ensure layouts adapt without becoming disorienting or unusable.

The role of QA teams

In most Agile and DevOps environments, QA engineers are positioned to catch accessibility issues early. This means incorporating accessibility checks into regression tests, sprint cycles, and exploratory testing sessions. It also means working closely with designers and developers to raise accessibility concerns before they go live.

Functional accessibility testing is not about perfection; it’s about practical inclusivity. If a user can’t complete a checkout flow, submit a form, or navigate your dashboard using assistive tech, it’s a functional failure—no different from a broken button or crashed page.

Non-functional accessibility testing

While functional testing checks whether users with disabilities can perform tasks, non-functional accessibility testing examines how digital products behave under various conditions that affect user experience. These include performance, usability, reliability, compatibility, and adherence to standards. For QA professionals, understanding this side of accessibility testing is essential for delivering software that isn’t just operable, but also efficient, consistent, and comfortable to use for everyone.

Contrary to functional testing, which helps assess whether a feature can be used, non-functional testing for accessibility is kind of like, “How well does it work for someone relying on assistive technology?” 

Let’s see some common use cases for non-functional accessibility testing.

Assistive technology performance

Many applications slow down or behave inconsistently when used with screen readers, magnifiers, or voice input tools. QA teams must assess whether pages load predictably and respond promptly to assistive tech commands. Lag, stuttering, or freezing under these conditions can degrade the user experience, even when the core functionality is intact.

Usability for users with disabilities

Beyond technical compatibility, QA should evaluate how intuitive the interface feels. Does a screen reader user have to work too hard to find the main content? Are navigation cues logical for users with cognitive disabilities? Does the tab order make sense across repeated sessions? Usability testing with real users—especially in usability labs or remote moderated studies—can uncover friction points that code-level audits miss.

Legal and regulatory compliance

This involves verifying that your software meets relevant accessibility standards, such as:

• WCAG 2.1 or 2.2 (internationally recognized guidelines),
• Section 508 (for U.S. federal agencies and contractors),
• or other legislation like the EN 301 549 standard in the EU.

Non-functional testing ensures that accessibility is not only present but also compliant with the formal criteria that regulators and procurement officers expect.

Cross-platform and cross-browser consistency

Accessibility issues often appear only on specific browsers, operating systems, or devices. A screen reader might behave differently on Chrome than on Firefox; voice navigation might work better on iOS than on Android. QA testers should validate that accessibility is consistent across environments, especially for critical workflows like authentication, transactions, and data entry.

Error prevention and recovery

Users with disabilities often have a harder time recovering from errors. Non-functional tests should examine how well the system helps users avoid mistakes and how it communicates when something goes wrong. Is error messaging easy to find and understand? Can users correct issues without restarting a process? These are subtle but vital aspects of accessible UX.

Why it matters

A product may technically comply with accessibility standards and still fall short in practice. Passing automated checks or meeting WCAG thresholds is only part of the equation. If users can’t complete basic steps—like filling out a form, navigating a menu, or accessing critical content with assistive technology—the experience is functionally inaccessible. Similarly, if the interface behaves unpredictably with a screen reader, breaks under certain conditions, or overwhelms users with poor usability, it fails on non-functional grounds.

Neglecting either side of accessibility testing can alienate users, limit product adoption, and expose organizations to reputational and legal risks. This is particularly critical in regulated sectors like healthcare, banking, education, and government services, where accessibility isn’t just expected—it’s often legally required.

For QA professionals and product decision-makers, accessibility must be treated as a core quality attribute—on par with performance, security, and reliability. Beyond compliance or inclusion, delivering robust, user-centered software that works for everyone, under real-world conditions, should be at the heart of software development and QA.

Implementing accessibility testing in the SDLC

Incorporating accessibility testing into the software development lifecycle (SDLC) is a key aspect of delivering high-quality, compliant, and user-centric digital products. However, many organizations still treat accessibility as a final check before release, which often results in costly rework, missed compliance goals, and poor user experiences.

To avoid this, accessibility must be embedded into each phase of the SDLC, from requirements gathering to post-launch monitoring. This ensures that functional and non-functional accessibility aspects are addressed proactively, rather than reactively.

1. Planning and requirements gathering

Start by setting clear accessibility goals based on relevant standards like WCAG 2.1 AA, ADA (for the U.S. market), or EN 301 549 (for the EU). Define accessibility as a non-negotiable quality attribute—just like performance or security.

At this stage:

• Collaborate with stakeholders to document accessibility requirements.
• Use personas that include users with disabilities.
• Set KPIs for accessibility testing coverage and compliance.

2. Design

Accessibility begins with inclusive design. Designers should apply accessible UI principles such as:

• Sufficient color contrast between text and background.
• Clear visual focus indicators for interactive elements.
• Logical content structure using semantic headings.
• Labels and instructions that support users with cognitive challenges.

QA teams can collaborate early with designers to review mockups or wireframes and provide feedback on potential accessibility concerns before development begins.

3. Development

During development, engineers should implement code that supports assistive technologies. This includes:

• Using semantic HTML and ARIA roles correctly.
• Ensuring all controls are accessible via keyboard.
• Avoiding time-based interactions that can’t be paused or extended.
• Testing with screen readers and other assistive tools during build.

Introducing component-level accessibility testing (especially in design systems or UI libraries) helps prevent the propagation of inaccessible elements across the product.

4. Testing

Accessibility testing must be part of both automated and manual QA processes.

• Automated tests: Use tools like Axe, Lighthouse, or WAVE to identify common issues such as missing alt text, color contrast failures, and form labeling problems. Integrate these tools into your CI/CD pipeline.
• Manual tests: Have QA testers validate keyboard navigation, screen reader performance, and other functional aspects. Use checklists to ensure consistency. Consider engaging real users with disabilities or accessibility experts for exploratory testing.
• Non-functional evaluations: Test the performance and behavior of your app across different assistive technologies, devices, browsers, and screen sizes. Use tools like VoiceOver, NVDA, or Dragon NaturallySpeaking to validate compatibility.

5. Deployment

Before release, run a final accessibility regression test. Ensure that any newly introduced features or changes haven’t broken accessibility elsewhere in the app. Prepare accessibility documentation if required, such as a VPAT (Voluntary Product Accessibility Template) for enterprise or government clients.

Make sure deployment notes include any known accessibility limitations and mitigation steps. Communicate openly with users and support teams.

6. Maintenance and continuous improvement

Accessibility is not a one-time task. As your product evolves, new accessibility issues can emerge.

• Monitor user feedback and accessibility-related support tickets.
• Periodically re-audit your application using updated tools and guidelines (especially after updates to WCAG or assistive tech).
• Train developers, QA, and design teams regularly to stay up to date on best practices.

Teams that treat accessibility as an ongoing quality metric will deliver more resilient, scalable, and inclusive digital products.

The roundup

Ensuring digital accessibility is a fundamental part of delivering high-quality, user-focused software. By addressing both functional and non-functional aspects of accessibility testing, QA teams can help ensure that digital products work not only in theory, but in the hands of real users with diverse abilities and needs.

Functional accessibility testing validates that users with disabilities can successfully interact with your software—completing tasks, navigating content, and accessing information with confidence. Non-functional testing, on the other hand, evaluates how reliably, efficiently, and comfortably the software performs in real-world scenarios, including usage with assistive technologies and across various platforms.

For product managers, decision-makers, and QA engineers, this means embedding accessibility into every phase of the software development lifecycle—from setting clear requirements and designing inclusively, to developing with semantic code and continuously testing with real assistive tools. The earlier and more systematic accessibility is addressed, the lower the cost of remediation—and the higher the payoff in usability, brand trust, and legal protection.

As digital accessibility continues to gain momentum worldwide—driven by user demand, evolving regulations, and increasing litigation—proactive accessibility testing offers a clear path to both ethical responsibility and business resilience.

At TestDevLab, we help companies integrate accessibility testing seamlessly into their QA workflows—from early-stage audits to ongoing compliance monitoring. Whether you’re looking to meet WCAG standards, improve usability for all users, or reduce the risk of accessibility-related legal issues, our experts can guide you every step of the way.