feat: Break up duplicate-id rule for ARIA+labels and for active elements

doc/rule-descriptions.md

@@ -23,7 +23,9 @@
 | definition-list | Ensures <dl> elements are structured correctly | Serious | cat.structure, wcag2a, wcag131 | true |
 | dlitem | Ensures <dt> and <dd> elements are contained by a <dl> | Serious | cat.structure, wcag2a, wcag131 | true |
 | document-title | Ensures each HTML document contains a non-empty <title> element | Serious | cat.text-alternatives, wcag2a, wcag242 | true |
-| duplicate-id | Ensures every id attribute value is unique | Moderate | cat.parsing, wcag2a, wcag411 | true |
+| duplicate-id-active | Ensures every id attribute value of active elements is unique | Serious | cat.parsing, wcag2a, wcag411 | true |
+| duplicate-id-aria | Ensures every id attribute value used in ARIA and in labels is unique | Critical | cat.parsing, wcag2a, wcag411 | true |
+| duplicate-id | Ensures every id attribute value is unique | Minor | cat.parsing, wcag2a, wcag411 | true |
 | empty-heading | Ensures headings have discernible text | Minor | cat.name-role-value, best-practice | true |
 | focus-order-semantics | Ensures elements in the focus order have an appropriate role | Minor | cat.keyboard, best-practice, experimental | true |
 | frame-tested | Ensures <iframe> and <frame> elements contain the axe-core script | Critical | cat.structure, review-item | true |

lib/checks/parsing/duplicate-id-active.json

@@ -0,0 +1,12 @@
+{
+  "id": "duplicate-id-active",
+  "evaluate": "duplicate-id.js",
+  "after": "duplicate-id-after.js",
+  "metadata": {
+    "impact": "serious",
+    "messages": {
+      "pass": "Document has no active elements that share the same id attribute",
+      "fail": "Document has active elements with the same id attribute: {{=it.data}}"
+    }
+  }
+}

lib/checks/parsing/duplicate-id-aria.json

@@ -0,0 +1,12 @@
+{
+  "id": "duplicate-id-aria",
+  "evaluate": "duplicate-id.js",
+  "after": "duplicate-id-after.js",
+  "metadata": {
+    "impact": "critical",
+    "messages": {
+      "pass": "Document has no elements referenced with ARIA or labels that share the same id attribute",
+      "fail": "Document has multiple elements referenced with ARIA or with the same id attribute: {{=it.data}}"
+    }
+  }
+}

lib/checks/shared/duplicate-id.json → lib/checks/parsing/duplicate-id.json

@@ -3,7 +3,7 @@
   "evaluate": "duplicate-id.js",
   "after": "duplicate-id-after.js",
   "metadata": {
-    "impact": "moderate",
+    "impact": "minor",
     "messages": {
       "pass": "Document has no elements that share the same id attribute",
       "fail": "Document has multiple elements with the same id attribute: {{=it.data}}"

lib/commons/aria/is-accessible-ref.js

@@ -0,0 +1,53 @@
+/* global aria, axe, dom */
+function findDomNode(node, functor) {
+	if (functor(node)) {
+		return node;
+	}
+	for (let i = 0; i < node.children.length; i++) {
+		const out = findDomNode(node.children[i], functor);
+		if (out) {
+			return out;
+		}
+	}
+}
+
+/**
+ * Check that a DOM node is a reference in the accessibility tree
+ * @param {Element} node
+ * @returns {Boolean}
+ */
+aria.isAccessibleRef = function isAccessibleRef(node) {
+	node = node.actualNode || node;
+	let root = dom.getRootNode(node);
+	root = root.documentElement || root; // account for shadow roots
+	const id = node.id;
+
+	// Get all idref(s) attributes on the lookup table
+	const refAttrs = Object.keys(aria.lookupTable.attributes).filter(attr => {
+		const { type } = aria.lookupTable.attributes[attr];
+		return /^idrefs?$/.test(type);
+	});
+
+	// Find the first element that IDREF(S) the node
+	let refElm = findDomNode(root, elm => {
+		if (elm.nodeType !== 1) {
+			// Elements only
+			return;
+		}
+		if (
+			elm.nodeName.toUpperCase() === 'LABEL' &&
+			elm.getAttribute('for') === id
+		) {
+			return true;
+		}
+		// See if there are any aria attributes that reference the node
+		return refAttrs.filter(attr => elm.hasAttribute(attr)).some(attr => {
+			const attrValue = elm.getAttribute(attr);
+			if (aria.lookupTable.attributes[attr].type === 'idref') {
+				return attrValue === id;
+			}
+			return axe.utils.tokenList(attrValue).includes(id);
+		});
+	});
+	return typeof refElm !== 'undefined';
+};

lib/rules/duplicate-id-active-matches.js

@@ -0,0 +1,8 @@
+const { dom, aria } = axe.commons;
+const id = node.getAttribute('id').trim();
+const idSelector = `*[id="${axe.utils.escapeSelector(id)}"]`;
+const idMatchingElms = Array.from(
+	dom.getRootNode(node).querySelectorAll(idSelector)
+);
+
+return idMatchingElms.some(dom.isFocusable) && !aria.isAccessibleRef(node);

lib/rules/duplicate-id-active.json

@@ -0,0 +1,20 @@
+{
+  "id": "duplicate-id-active",
+  "selector": "[id]",
+  "matches": "duplicate-id-active-matches.js",
+  "excludeHidden": false,
+  "tags": [
+    "cat.parsing",
+    "wcag2a",
+    "wcag411"
+  ],
+  "metadata": {
+    "description": "Ensures every id attribute value of active elements is unique",
+    "help": "IDs of active elements must be unique"
+  },
+  "all": [],
+  "any": [
+    "duplicate-id-active"
+  ],
+  "none": []
+}

lib/rules/duplicate-id-aria-matches.js

@@ -0,0 +1 @@
+return axe.commons.aria.isAccessibleRef(node);

lib/rules/duplicate-id-aria.json

@@ -0,0 +1,20 @@
+{
+  "id": "duplicate-id-aria",
+  "selector": "[id]",
+  "matches": "duplicate-id-aria-matches.js",
+  "excludeHidden": false,
+  "tags": [
+    "cat.parsing",
+    "wcag2a",
+    "wcag411"
+  ],
+  "metadata": {
+    "description": "Ensures every id attribute value used in ARIA and in labels is unique",
+    "help": "IDs used in ARIA and labels must be unique"
+  },
+  "all": [],
+  "any": [
+    "duplicate-id-aria"
+  ],
+  "none": []
+}

lib/rules/duplicate-id-misc-matches.js

@@ -0,0 +1,11 @@
+const { dom, aria } = axe.commons;
+const id = node.getAttribute('id').trim();
+const idSelector = `*[id="${axe.utils.escapeSelector(id)}"]`;
+const idMatchingElms = Array.from(
+	dom.getRootNode(node).querySelectorAll(idSelector)
+);
+
+return (
+	idMatchingElms.every(elm => !dom.isFocusable(elm)) &&
+	!aria.isAccessibleRef(node)
+);

lib/rules/duplicate-id.json

@@ -1,6 +1,7 @@
 {
   "id": "duplicate-id",
   "selector": "[id]",
+  "matches": "duplicate-id-misc-matches.js",
   "excludeHidden": false,
   "tags": [
     "cat.parsing",

test/commons/aria/is-accessible-ref.js

@@ -0,0 +1,96 @@
+describe('aria.isAccessibleRef', function() {
+	'use strict';
+
+	var __atrs;
+	var fixture = document.getElementById('fixture');
+	var isAccessibleRef = axe.commons.aria.isAccessibleRef;
+	var shadowSupport = axe.testUtils.shadowSupport.v1;
+
+	function setLookup(attrs) {
+		axe.commons.aria.lookupTable.attributes = attrs;
+	}
+
+	afterEach(function() {
+		fixture.innerHTML = '';
+		__atrs = axe.commons.aria.lookupTable.attributes;
+	});
+
+	afterEach(function() {
+		axe.commons.aria.lookupTable.attributes = __atrs;
+	});
+
+	it('returns false by default', function() {
+		fixture.innerHTML = '<div id="foo"><div>';
+		var node = document.getElementById('foo');
+		assert.isFalse(isAccessibleRef(node));
+	});
+
+	it('returns true for IDs used in aria IDREF attributes', function() {
+		setLookup({ 'aria-foo': { type: 'idref' } });
+		fixture.innerHTML = '<div aria-foo="foo"></div><i id="foo"></i>';
+		var node = document.getElementById('foo');
+		assert.isTrue(isAccessibleRef(node));
+	});
+
+	it('returns true for IDs used in aria IDREFS attributes', function() {
+		setLookup({ 'aria-bar': { type: 'idrefs' } });
+		fixture.innerHTML =
+			'<div aria-bar="foo bar"></div><i id="foo"></i><b id="bar"></b>';
+
+		var node1 = document.getElementById('foo');
+		var node2 = document.getElementById('bar');
+		assert.isTrue(isAccessibleRef(node1));
+		assert.isTrue(isAccessibleRef(node2));
+	});
+
+	it('returns true for IDs used in label[for] attributes', function() {
+		setLookup({ 'aria-foo': { type: 'idref' } });
+		fixture.innerHTML = '<label for="baz">baz</label><input id="baz">';
+		var node = document.getElementById('baz');
+		assert.isTrue(isAccessibleRef(node));
+	});
+
+	(shadowSupport ? it : xit)('works inside shadow DOM', function() {
+		setLookup({ 'aria-bar': { type: 'idref' } });
+		fixture.innerHTML = '<div id="foo"></div>';
+
+		var shadow = document.getElementById('foo').attachShadow({ mode: 'open' });
+		shadow.innerHTML = '<div aria-bar="bar"></div><b id="bar"></b>';
+
+		var node = shadow.getElementById('bar');
+		assert.isTrue(isAccessibleRef(node));
+	});
+
+	(shadowSupport ? it : xit)(
+		'returns false for IDREFs inside shadow DOM',
+		function() {
+			setLookup({ 'aria-foo': { type: 'idrefs' } });
+			fixture.innerHTML = '<div id="foo"><div id="bar"></div></div>';
+			var node1 = document.getElementById('foo');
+			var node2 = document.getElementById('bar');
+
+			var shadow = node1.attachShadow({ mode: 'open' });
+			shadow.innerHTML = '<div aria-foo="foo bar"><slot></slot></div>';
+
+			assert.isFalse(isAccessibleRef(node1));
+			assert.isFalse(isAccessibleRef(node2));
+		}
+	);
+
+	(shadowSupport ? it : xit)(
+		'returns false for IDREFs outside shadow DOM',
+		function() {
+			setLookup({ 'aria-bar': { type: 'idref' } });
+			fixture.innerHTML =
+				'<div id="foo" aria-bar="bar"><div aria-bar="bar"></div></div>';
+
+			var shadow = document
+				.getElementById('foo')
+				.attachShadow({ mode: 'open' });
+			shadow.innerHTML = '<div id="bar"><slot></slot></div>';
+
+			var node = shadow.getElementById('bar');
+			assert.isFalse(isAccessibleRef(node));
+		}
+	);
+});

test/integration/rules/duplicate-id-active/duplicate-id-active.html

@@ -0,0 +1,19 @@
+<p id="ignore1">This is my first paragraph with this ID.</p>
+<div style="display:none">
+  <p id="ignore1">This is my second paragraph with this ID.</p>
+</div>
+
+<button id="fail1" class="fail1"></button>
+<button id="fail1"></button>
+
+<input id="pass1" />
+<textarea id="pass2"></textarea>
+<select id="pass3"></select>
+<div tabindex="0" id="pass4"></div>
+
+<span id="ignored1"></span>
+<button id="ignored2"></button>
+<div aria-labelledby="ignored1 ignored2"></div>
+<input id="ignore3" type="hidden" />
+<button id="ignore4" disabled></button>
+<button id="ignore5" style="display:none"></button>

test/integration/rules/duplicate-id-active/duplicate-id-active.json

@@ -0,0 +1,6 @@
+{
+	"description": "duplicate-id-active test",
+	"rule": "duplicate-id-active",
+	"violations": [[".fail1"]],
+	"passes": [["#pass1"], ["#pass2"], ["#pass3"], ["#pass4"]]
+}

test/integration/rules/duplicate-id-aria/duplicate-id-aria.html

@@ -0,0 +1,19 @@
+<p id="ignore1">This is my first paragraph with this ID.</p>
+<div style="display:none">
+  <p id="ignore1">This is my second paragraph with this ID.</p>
+</div>
+
+<input id="ignore2" />
+<textarea id="ignore3"></textarea>
+<select id="ignore4"></select>
+<div tabindex="0" id="ignore5"></div>
+
+<span id="fail1" class="fail1"></span>
+<button id="fail1"></button>
+<span id="pass1"></span>
+<button id="pass2"></button>
+<div aria-labelledby="fail1 pass1 pass2"></div>
+
+<input id="ignore6" type="hidden" />
+<button id="ignore7" disabled></button>
+<button id="ignore8" style="display:none"></button>

test/integration/rules/duplicate-id-aria/duplicate-id-aria.json

@@ -0,0 +1,6 @@
+{
+	"description": "duplicate-id-aria test",
+	"rule": "duplicate-id-aria",
+	"violations": [[".fail1"]],
+	"passes": [["#pass1"], ["#pass2"]]
+}

test/integration/rules/duplicate-id/duplicate-id.html

@@ -1,5 +1,17 @@
-<p id="dupe">This is my first paragraph with this ID.</p>
+<p id="fail1" class="fail1">This is my first paragraph with this ID.</p>
 <div style="display:none">
-  <p id="dupe">This is my second paragraph with this ID.</p>
+  <p id="fail1">This is my second paragraph with this ID.</p>
 </div>
-<p id="single">This is my only paragraph with this ID.</p>
+
+<input id="ignored1" />
+<textarea id="ignored2"></textarea>
+<select id="ignored3"></select>
+<div tabindex="0" id="ignored4"></div>
+
+<span id="ignored5"></span>
+<button id="ignored6"></button>
+<div aria-labelledby="ignored5 ignored6"></div>
+
+<input id="pass1" type="hidden" />
+<button id="pass2" disabled></button>
+<button id="pass3" style="display:none"></button>

test/integration/rules/duplicate-id/duplicate-id.json

@@ -1,6 +1,6 @@
 {
 	"description": "duplicate-id test",
 	"rule": "duplicate-id",
-	"violations": [["#fixture > p:nth-child(1)"]],
-	"passes": [["#fixture"], ["#single"]]
+	"violations": [[".fail1"]],
+	"passes": [["#fixture"], ["#pass1"], ["#pass2"], ["#pass3"]]
 }