--- /dev/null
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Steps definitions to open and close action menus.
+ *
+ * @package core
+ * @category test
+ * @copyright 2020 Andrew Nicols <andrew@nicols.co.uk>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+use Behat\Mink\Exception\{DriverException, ExpectationException};
+
+// NOTE: no MOODLE_INTERNAL test here, this file may be required by behat before including /config.php.
+
+require_once(__DIR__ . '/../../behat/behat_base.php');
+
+/**
+ * Steps definitions to assist with accessibility testing.
+ *
+ * @package core
+ * @category test
+ * @copyright 2020 Andrew Nicols <andrew@nicols.co.uk>
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class behat_accessibility extends behat_base {
+
+ /**
+ * Run the axe-core accessibility tests.
+ *
+ * There are standard tags to ensure WCAG 2.1 A, WCAG 2.1 AA, and Section 508 compliance.
+ * It is also possible to specify any desired optional tags.
+ *
+ * The list of available tags can be found at
+ * https://github.com/dequelabs/axe-core/blob/v3.5.5/doc/rule-descriptions.md.
+ *
+ * @Then the page should meet accessibility standards
+ * @Then the page should meet accessibility standards with :extratags extra tests
+ * @Then the page should meet :standardtags accessibility standards
+ * @param string $standardtags Comma-separated list of standard tags to run
+ * @param string $extratags Comma-separated list of tags to run in addition to the standard tags
+ */
+ public function run_axe_validation_for_tags(string $standardtags = '', string $extratags = ''): void {
+ $this->run_axe_for_tags(
+ // Turn the comma-separated string into an array of trimmed values, filtering out empty values.
+ array_filter(array_map('trim', explode(',', $standardtags))),
+ array_filter(array_map('trim', explode(',', $extratags)))
+ );
+ }
+
+ /**
+ * Run the Axe tests.
+ *
+ * See https://github.com/dequelabs/axe-core/blob/develop/doc/rule-descriptions.md for details of the supported
+ * tags.
+ *
+ * @param array $standardtags The list of standard tags to run
+ * @param array $extratags The list of tags, in addition to the standard tags, to run
+ */
+ protected function run_axe_for_tags(array $standardtags = [], array $extratags = []): void {
+ if (!$this->has_tag('accessibility')) {
+ throw new DriverException(
+ 'Accessibility tests using Axe must have the @accessibility tag on either the scenario or feature.'
+ );
+ }
+
+ $this->require_javascript();
+
+ $axeurl = (new \moodle_url('/lib/behat/axe/axe.min.js'))->out(false);
+ $axeconfig = $this->get_axe_config_for_tags($standardtags, $extratags);
+ $runaxe = <<<EOF
+(axeurl => {
+ const runTests = () => {
+ const axeTag = document.querySelector('script[data-purpose="axe"]');
+ axeTag.dataset.results = null;
+
+ axe.run({$axeconfig})
+ .then(results => {
+ axeTag.dataset.results = JSON.stringify({
+ violations: results.violations,
+ exception: null,
+ });
+ })
+ .catch(exception => {
+ axeTag.dataset.results = JSON.stringify({
+ violations: [],
+ exception: exception,
+ });
+ });
+ };
+
+ if (document.querySelector('script[data-purpose="axe"]')) {
+ runTests();
+ } else {
+ // Inject the axe content.
+ const axeTag = document.createElement('script');
+ axeTag.src = axeurl,
+ axeTag.dataset.purpose = 'axe';
+
+ axeTag.onload = () => runTests();
+ document.head.append(axeTag);
+ }
+})('{$axeurl}');
+EOF;
+
+ $this->execute_script($runaxe);
+
+ $getresults = <<<EOF
+return (() => {
+ const axeTag = document.querySelector('script[data-purpose="axe"]');
+ return axeTag.dataset.results;
+})()
+EOF;
+
+ for ($i = 0; $i < self::get_extended_timeout() * 10; $i++) {
+ $results = json_decode($this->evaluate_script($getresults));
+ if ($results) {
+ break;
+ }
+ }
+
+ if (empty($results)) {
+ throw new \Exception('No data');
+ }
+
+ if ($results->exception !== null) {
+ throw new ExpectationException($results->exception, $this->session);
+ }
+
+ $violations = $results->violations;
+ if (!count($violations)) {
+ return;
+ }
+
+ $violationdata = "Accessibility violations found:\n";
+ foreach ($violations as $violation) {
+ $nodedata = '';
+ foreach ($violation->nodes as $node) {
+ $failedchecks = [];
+ foreach (array_merge($node->any, $node->all, $node->none) as $check) {
+ $failedchecks[$check->id] = $check->message;
+ }
+
+ $nodedata .= sprintf(
+ " - %s:\n %s\n\n",
+ implode(', ', $failedchecks),
+ implode("\n ", $node->target)
+ );
+ }
+
+ $violationdata .= sprintf(
+ " %.03d violations of '%s' (severity: %s)\n%s\n",
+ count($violation->nodes),
+ $violation->description,
+ $violation->impact,
+ $nodedata
+ );
+ }
+
+ throw new ExpectationException($violationdata, $this->getSession());
+ }
+
+ /**
+ * Get the configuration to use with Axe.
+ *
+ * See https://github.com/dequelabs/axe-core/blob/develop/doc/rule-descriptions.md for details of the rules.
+ *
+ * @param array|null $standardtags The list of standard tags to run
+ * @param array|null $extratags The list of tags, in addition to the standard tags, to run
+ * @return string The JSON-encoded configuration.
+ */
+ protected function get_axe_config_for_tags(?array $standardtags = null, ?array $extratags = null): string {
+ if (empty($standardtags)) {
+ $standardtags = [
+ // Meet WCAG 2.1 A requirements.
+ 'wcag2a',
+
+ // Meet WCAG 2.1 AA requirements.
+ 'wcag2aa',
+
+ // Meet Section 508 requirements.
+ // See https://www.epa.gov/accessibility/what-section-508 for detail.
+ 'section508',
+
+ // Ensure that ARIA attributes are correctly defined.
+ 'cat.aria',
+
+ // Requiremetns for sensory and visual cues.
+ // These largely related to viewport scale and zoom functionality.
+ 'cat.sensory-and-visual-cues',
+
+ // Meet WCAG 1.3.4 requirements for orientation.
+ // See https://www.w3.org/WAI/WCAG21/Understanding/orientation.html for detail.
+ 'wcag134',
+ ];
+ }
+
+ return json_encode([
+ 'runOnly' => [
+ 'type' > 'tag',
+ 'values' => array_merge($standardtags, $extratags),
+ ],
+ ]);
+ }
+}
