Test Rule: Image button has non-empty accessible name

Description

This rule checks that each image button element has a non-empty accessible name.

Applicability

This rule applies to any input element with a type attribute value of image, and that is included in the accessibility tree.

Expectation

Each target element has an accessible name that is neither empty (""), nor the default name for this element (localized version of “Submit Query”).

Assumptions

• This rule assumes that all image buttons are user interface components as defined by WCAG 2.
• This rule assumes that the default name for image buttons (“Submit Query”), as defined by the HTML Accessibility API Mapping, is never descriptive.

Accessibility Support

There is a known combination of a popular browser and assistive technology that does not by default support title as an accessible name.

Background

Related rules

• Button has non-empty accessible name

Bibliography

• Understanding Success Criterion 1.1.1: Non-text Content
• Understanding Success Criterion 4.1.2: Name, Role, Value
• WCAG Technique H36: Using alt attributes on images used as submit buttons
• HTML Accessibility API Mappings for computing the accessible name of image buttons

Accessibility Requirements Mapping

• 1.1.1 Non-text Content (Level A)

  • Learn more about 1.1.1 Non-text Content
  • Required for conformance to WCAG 2.0 and later on level A and higher.
  • Outcome mapping:
    • Any failed outcomes: success criterion is not satisfied
    • All passed outcomes: success criterion needs further testing
    • An inapplicable outcome: success criterion needs further testing
• 4.1.2 Name, Role, Value (Level A)

  • Learn more about 4.1.2 Name, Role, Value
  • Required for conformance to WCAG 2.0 and later on level A and higher.
  • Outcome mapping:
    • Any failed outcomes: success criterion is not satisfied
    • All passed outcomes: success criterion needs further testing
    • An inapplicable outcome: success criterion needs further testing
• G94: Providing short text alternative for non-text content that serves the same purpose and presents the same information as the non-text content

  • Learn more about technique G94
  • Not required for conformance to any W3C accessibility recommendation.
  • Outcome mapping:
    • Any failed outcomes: technique is not satisfied
    • All passed outcomes: technique needs further testing
    • An inapplicable outcome: technique needs further testing
• G95: Providing short text alternatives that provide a brief description of the non-text content

  • Learn more about technique G95
  • Not required for conformance to any W3C accessibility recommendation.
  • Outcome mapping:
    • Any failed outcomes: technique is not satisfied
    • All passed outcomes: technique needs further testing
    • An inapplicable outcome: technique needs further testing

Input Aspects

The following aspects are required in using this rule.

• DOM Tree
• CSS Styling

Test Cases

Passed

Passed Example 1

The image button has an accessible name through the alt attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" alt="Search" />

Passed Example 2

The image button has an accessible name through the aria-label attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-label="Search" />

Passed Example 3

The image button has an accessible name through the title attribute.

note: The title attribute may not always be accessibility supported.

<input type="image" src="/test-assets/shared/search-icon.svg" title="Search" />

Passed Example 4

The image button has an accessible name through the aria-labelledby attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-labelledby="id1" />
<div id="id1">Search</div>

Failed

Failed Example 1

The image button element has an accessible name equal to the default “Submit Query”. The name attribute can not be used to provide an accessible name.

<input type="image" name="search" src="/test-assets/shared/search-icon.svg" />

Failed Example 2

The image button has an empty alt attribute, and no other attributes that can give it an accessible name, hence its name is the default “Submit Query”.

<input type="image" src="/test-assets/shared/search-icon.svg" alt="" />

Failed Example 3

The image button has an aria-labelledby attribute, but the referenced element does not exist. This gives the button the default accessible name of “Submit Query”.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-labelledby="non-existing" />

Inapplicable

Inapplicable Example 1

The button element is not an image button. Success Criterion 1.1.1 Non-text Content can not fail text buttons. Only non-text content is applicable.

<button>My button</button>

Inapplicable Example 2

The input element with the type attribute value of button is not an image button. Success Criterion 1.1.1 Non-text Content can not fail text buttons. Only non-text content is applicable.

<input type="button" value="My button" />

Inapplicable Example 3

The button element is tested separately from the img element. Success Criterion 4.1.2 Name, Role, Value is applied to the button, whereas the image is tested under Success Criterion 1.1.1 Non-text Content

<button><img src="/test-assets/shared/search-icon.svg" alt="Search" /></button>

Inapplicable Example 4

The img element is not a user interface component, and so is not tested for Success Criterion 4.1.2 Name, Role, Value.

<img src="/test-assets/shared/w3c-logo.png" alt="W3C logo" />

Inapplicable Example 5

The image button is ignored by assistive technologies because it is not included in the accessibility tree. These are not required to have an accessible name. If at some future state of the page the element gets included in the accessibility tree, an accessible name will be necessary.

<input type="image" src="/test-assets/shared/search-icon.svg" style="display: none;" />

Glossary

Accessible Name

The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.

The accessible name is calculated using the accessible name and description computation.

For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).

For more details, see examples of accessible name.

Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.

Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

• For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, “an input element with a type attribute value of Text” can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
• For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
• For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
• For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
• For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
• For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Focusable

Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

• Inapplicable: No part of the test subject matches the applicability
• Passed: A test target meets all expectations
• Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such “interim” results can be expressed with the incomplete outcome.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

• has a hidden attribute; or
• has a computed CSS property display of none; or
• has an aria-hidden attribute set to true

Note: Contrarily to the other conditions, the visibility CSS property may be reverted by descendants.

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date.

Changelog

This is the first version of this ACT rule.