new_audit: td-has-header (#15051)

Co-authored-by: Brendan Kenny <[email protected]>

cli/test/smokehouse/test-definitions/a11y.js

@@ -698,6 +698,22 @@ const expectations = {
           ],
         },
       },
+      'td-has-header': {
+        score: 0,
+        details: {
+          items: [
+            {
+              node: {
+                'type': 'node',
+                'selector': 'body > section > table#td-has-header',
+                'snippet': '<table id="td-has-header">',
+                'explanation': 'Fix all of the following:\n  Some non-empty data cells do not have table headers',
+                'nodeLabel': 'FOO\tFOO\tFOO\tFOO\nfoo\tfoo\tfoo\tfoo\nfoo\tfoo\tfoo\tfoo\nfoo\tfoo\tfoo\tfoo',
+              },
+            },
+          ],
+        },
+      },
       'td-headers-attr': {
         score: 0,
         details: {

core/audits/accessibility/td-has-header.js

@@ -0,0 +1,45 @@
+/**
+ * @license Copyright 2023 The Lighthouse Authors. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
+ */
+
+/**
+ * @fileoverview Ensure that large tables have `[header]` attributes.
+ * See base class in axe-audit.js for audit() implementation.
+ */
+
+import AxeAudit from './axe-audit.js';
+import * as i18n from '../../lib/i18n/i18n.js';
+
+const UIStrings = {
+  /** Title of an accesibility audit that evaluates if all large table elements use the headers HTML attribute. This title is descriptive of the successful state and is shown to users when no user action is required. */
+  title: '`<td>` elements in a large `<table>` have one or more table headers.',
+  /** Title of an accesibility audit that evaluates if all large table elements use the headers HTML attribute. This title is descriptive of the failing state and is shown to users when there is a failure that needs to be addressed. */
+  failureTitle: '`<td>` elements in a large `<table>` do not have table headers.',
+  /** Description of a Lighthouse audit that tells the user *why* they should try to pass. This is displayed after a user expands the section to see more. No character length limits. The last sentence starting with 'Learn' becomes link text to additional documentation. */
+  description: 'Screen readers have features to make navigating tables easier. Ensuring ' +
+      'that `<td>` elements in a large table (3 or more cells in width and height) have an ' +
+      'associated table header may improve the experience for screen reader users. ' +
+      '[Learn more about table headers](https://dequeuniversity.com/rules/axe/4.7/td-has-header).',
+};
+
+const str_ = i18n.createIcuMessageFn(import.meta.url, UIStrings);
+
+class TDHasHeader extends AxeAudit {
+  /**
+   * @return {LH.Audit.Meta}
+   */
+  static get meta() {
+    return {
+      id: 'td-has-header',
+      title: str_(UIStrings.title),
+      failureTitle: str_(UIStrings.failureTitle),
+      description: str_(UIStrings.description),
+      requiredArtifacts: ['Accessibility'],
+    };
+  }
+}
+
+export default TDHasHeader;
+export {UIStrings};

core/config/default-config.js

@@ -273,6 +273,7 @@ const defaultConfig = {
     'accessibility/meta-viewport',
     'accessibility/object-alt',
     'accessibility/tabindex',
+    'accessibility/td-has-header',
     'accessibility/td-headers-attr',
     'accessibility/th-has-data-cells',
     'accessibility/valid-lang',
@@ -537,6 +538,7 @@ const defaultConfig = {
         {id: 'meta-viewport', weight: 10, group: 'a11y-best-practices'},
         {id: 'object-alt', weight: 3, group: 'a11y-names-labels'},
         {id: 'tabindex', weight: 3, group: 'a11y-navigation'},
+        {id: 'td-has-header', weight: 10, group: 'a11y-tables-lists'},
         {id: 'td-headers-attr', weight: 3, group: 'a11y-tables-lists'},
         {id: 'th-has-data-cells', weight: 3, group: 'a11y-tables-lists'},
         {id: 'valid-lang', weight: 3, group: 'a11y-language'},

core/gather/gatherers/accessibility.js

@@ -45,7 +45,7 @@ async function runA11yChecks() {
       'meta-viewport': {enabled: true},
       'duplicate-id': {enabled: false},
       'table-fake-caption': {enabled: false},
-      'td-has-header': {enabled: false},
+      'td-has-header': {enabled: true},
       'marquee': {enabled: false},
       'area-alt': {enabled: false},
       'html-xml-lang-mismatch': {enabled: false},