Andrew Nicols
277 lines
10 KiB
PHP
277 lines
10 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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use Behat\Mink\Exception\DriverException;
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use Behat\Mink\Exception\ExpectationException;
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use Behat\Mink\Element\NodeElement;
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// NOTE: no MOODLE_INTERNAL test here, this file may be required by behat before including /config.php.
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require_once(__DIR__ . '/../../behat/behat_base.php');
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/**
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* Steps definitions to assist with accessibility testing.
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*
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* @package core
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* @category test
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* @copyright 2020 Andrew Nicols <andrew@nicols.co.uk>
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class behat_accessibility extends behat_base {
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/**
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* Run the axe-core accessibility tests.
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*
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* There are standard tags to ensure WCAG 2.1 A, WCAG 2.1 AA, and Section 508 compliance.
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* It is also possible to specify any desired optional tags.
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*
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* See {@link https://github.com/dequelabs/axe-core/blob/v4.10.2/doc/rule-descriptions.md} for the list of available tags
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*
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* @Then the page should meet accessibility standards
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* @Then the page should meet accessibility standards with :extratags extra tests
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* @Then the page should meet :standardtags accessibility standards
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* @param string $standardtags Comma-separated list of standard tags to run
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* @param string $extratags Comma-separated list of tags to run in addition to the standard tags
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*/
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public function run_axe_validation_for_tags(string $standardtags = '', string $extratags = ''): void {
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$this->run_axe_for_tags(
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// Turn the comma-separated string into an array of trimmed values, filtering out empty values.
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array_filter(array_map('trim', explode(',', $standardtags))),
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array_filter(array_map('trim', explode(',', $extratags)))
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);
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}
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/**
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* Run the axe-core accessibility tests for a page region.
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*
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* There are standard tags to ensure WCAG 2.1 A, WCAG 2.1 AA, and Section 508 compliance.
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* It is also possible to specify any desired optional tags.
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*
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* See {@link https://github.com/dequelabs/axe-core/blob/v4.10.0/doc/rule-descriptions.md} for the list of available tags
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*
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* @Then the :element :selector should meet accessibility standards
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* @Then the :element :selector should meet accessibility standards with :extratags extra tests
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* @Then the :element :selector should meet :standardtags accessibility standards
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* @param string $element The element to run the tests on
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* @param string $selector The selector to use to find the element
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* @param string $standardtags Comma-separated list of standard tags to run
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* @param string $extratags Comma-separated list of tags to run in addition to the standard tags
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*/
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public function run_axe_validation_for_tags_within_element(
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string $element,
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string $selector,
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string $standardtags = '',
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string $extratags = '',
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): void {
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$node = $this->get_selected_node($selector, $element);
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$this->run_axe_for_tags(
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// Turn the comma-separated string into an array of trimmed values, filtering out empty values.
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array_filter(array_map('trim', explode(',', $standardtags))),
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array_filter(array_map('trim', explode(',', $extratags))),
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$node,
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);
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}
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/**
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* Run the Axe tests.
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*
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* See {@see behat_accessibility::run_axe_validation_for_tags} for details of the supported tags.
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*
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* @param array $standardtags The list of standard tags to run
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* @param array $extratags The list of tags, in addition to the standard tags, to run
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* @param null|NodeElement $containerelement The element to run the tests on
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*/
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protected function run_axe_for_tags(
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array $standardtags = [],
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array $extratags = [],
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?NodeElement $containerelement = null,
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): void {
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if (!behat_config_manager::get_behat_run_config_value('axe')) {
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return;
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}
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if (!$this->has_tag('accessibility')) {
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throw new DriverException(
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'Accessibility tests using Axe must have the @accessibility tag on either the scenario or feature.'
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);
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}
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$this->require_javascript();
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$axeurl = (new \moodle_url('/lib/behat/axe/axe.min.js'))->out(false);
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$axeconfig = $this->get_axe_config_for_tags($standardtags, $extratags);
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$xpath = '';
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if ($containerelement) {
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$xpath = $this->prepare_xpath_for_javascript($containerelement->getXpath());
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}
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$runaxe = <<<EOF
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(axeurl => {
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const runTests = () => {
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const axeTag = document.querySelector('script[data-purpose="axe"]');
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axeTag.dataset.results = null;
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const getRun = () => {
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const xpath = "{$xpath}";
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if (xpath.length) {
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const targetElements = [];
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const results = document.evaluate(xpath, document, null, XPathResult.ANY_TYPE, null);
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let targetElement = results.iterateNext();
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while (targetElement) {
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targetElements.push(targetElement);
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targetElement = results.iterateNext();
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}
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return axe.run(targetElements, {$axeconfig});
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}
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return axe.run({$axeconfig});
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};
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getRun()
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.then(results => {
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axeTag.dataset.results = JSON.stringify({
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violations: results.violations,
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exception: null,
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});
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})
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.catch(exception => {
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axeTag.dataset.results = JSON.stringify({
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violations: [],
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exception: exception,
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});
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});
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};
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if (document.querySelector('script[data-purpose="axe"]')) {
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runTests();
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} else {
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// Inject the axe content.
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const axeTag = document.createElement('script');
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axeTag.src = axeurl,
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axeTag.dataset.purpose = 'axe';
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axeTag.onload = () => runTests();
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document.head.append(axeTag);
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}
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})('{$axeurl}');
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EOF;
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$this->execute_script($runaxe);
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$getresults = <<<EOF
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return (() => {
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const axeTag = document.querySelector('script[data-purpose="axe"]');
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return axeTag.dataset.results;
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})()
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EOF;
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for ($i = 0; $i < self::get_extended_timeout() * 10; $i++) {
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$results = json_decode($this->evaluate_script($getresults) ?? '');
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if ($results) {
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break;
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}
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}
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if (empty($results)) {
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throw new \Exception('No data');
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}
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if ($results->exception !== null) {
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throw new ExpectationException($results->exception, $this->getSession());
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}
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$violations = $results->violations;
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if (!count($violations)) {
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return;
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}
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$violationdata = "Accessibility violations found:\n";
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foreach ($violations as $violation) {
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$nodedata = '';
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foreach ($violation->nodes as $node) {
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$failedchecks = [];
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foreach (array_merge($node->any, $node->all, $node->none) as $check) {
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$failedchecks[$check->id] = $check->message;
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}
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$nodedata .= sprintf(
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" - %s:\n %s\n\n",
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implode(', ', $failedchecks),
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implode("\n ", $node->target)
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);
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}
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$violationdata .= sprintf(
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" %.03d violations of rule '%s' found (severity: %s)\n",
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count($violation->nodes),
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$violation->id,
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$violation->impact,
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);
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$violationdata .= " {$violation->help}\n";
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$violationdata .= " {$violation->description}\n";
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$violationdata .= " {$violation->helpUrl}\n";
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$violationdata .= $nodedata;
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}
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throw new ExpectationException($violationdata, $this->getSession());
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}
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/**
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* Get the configuration to use with Axe.
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*
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* See {@see behat_accessibility::run_axe_validation_for_tags} for details of the rules.
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*
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* @param array|null $standardtags The list of standard tags to run
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* @param array|null $extratags The list of tags, in addition to the standard tags, to run
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* @return string The JSON-encoded configuration.
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*/
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protected function get_axe_config_for_tags(?array $standardtags = null, ?array $extratags = null): string {
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if (empty($standardtags)) {
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$standardtags = [
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// Meet WCAG 2.2 Level A success criteria.
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'wcag2a',
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'wcag21a',
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'wcag22a',
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// Meet WCAG 2.2 Level AA success criteria.
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'wcag2aa',
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'wcag21aa',
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'wcag22aa',
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// Meet Section 508 requirements.
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// See https://www.epa.gov/accessibility/what-section-508 for detail.
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'section508',
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// Ensure that ARIA attributes are correctly defined.
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'cat.aria',
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// Requirements for sensory and visual cues.
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// These largely related to viewport scale and zoom functionality.
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'cat.sensory-and-visual-cues',
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// Meet WCAG 1.3.4 requirements for orientation.
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// See https://www.w3.org/WAI/WCAG21/Understanding/orientation.html for detail.
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'wcag134',
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];
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}
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return json_encode([
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'runOnly' => [
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'type' > 'tag',
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'values' => array_merge($standardtags, $extratags),
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],
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]);
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}
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}
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