New rule: SC4-1-1-unique-attrs

[WilcoFiers]

---

name: attributes are not duplicated
rule_type: atomic
description: |
This rule checks that HTML and SVG starting tags do not contain duplicated attributes.

success_criterion:

• 4.1.1 # Parsing

test_aspects:

• Source code

authors:

• Wilco Fiers
• Emma Pratt Richens

---

Applicability

The rule applies to any starting tag in an HTML or SVG file.

Note: This rule cannot be tested on the DOM Tree because the browser ignores duplicated attributes.

Expectation

For each test target, there are no duplicated attributes.

Assumptions

There are currently no assumptions.

Accessibility support

There are no major accessibility support issues known for this rule.

Background

• • H94: Ensuring that elements do not contain duplicate attributes

Test Cases

Passed

Passed example 1

No attributes are duplicated.

<img src="image.jpg" alt="" />

Passed example 2

No attributes, therefore no attributes are duplicated.

<br />

Passed example 3

Empty attributes, no attributes are duplicated.

<input type="checkbox" disabled readonly />

Passed example 4

SVG, no attributes are duplicated.

<svg>
  <line x1="0" y1="0" x2="200" y2="200" style="stroke-width:2" />
</svg>

Passed example 5

Script, no attributes are duplicated. HTML or SVG code within a script should be ignored.

<script>
	var foo = '<img src="image.jpg" alt="" alt="image" />'
</script>

Failed

Failed example 1

At least one attribute is duplicated.

<img src="image.jpg" alt="" alt="image" />

Failed example 2

Empty attributes, at least one attribute is duplicated.

<input type="checkbox" disabled="disabled" disabled readonly />

Failed example 3

SVG, at least one attribute is duplicated.

<svg>
  <line x1="0" y1="0" x1="200" y1="200" style="stroke-width:2" />
</svg>

Inapplicable

Inapplicable example 1

Code is XML, and not an HTML or SVG document.

<?xml version="1.0" encoding="UTF-8"?>
<earl:TestResult rdf:about="#result"></earl>

Inapplicable example 2

Code is JavaScript, and not an HTML or SVG document.

var foo = '<img src="image.jpg" alt="" alt="image" />'

[WilcoFiers]

Source code

A set of instructions and statements to be interpreted by a computer. Each source code file has a file type. The method for determining file type depends on the method through which the file is loaded.

[EmmaJP]

Resolved by pull request #332