Proyectos de Subversion Moodle

<?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/>.

/**

 * A trait containing functionality used by the behat base context, and form fields.

 *

 * @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\Element\NodeElement;

use Behat\Mink\Element\Element;

use Behat\Mink\Exception\DriverException;

use Behat\Mink\Exception\ExpectationException;

use Behat\Mink\Exception\ElementNotFoundException;

use Behat\Mink\Exception\NoSuchWindowException;

use Behat\Mink\Session;

use Behat\Testwork\Hook\Scope\HookScope;

use Facebook\WebDriver\Exception\ScriptTimeoutException;

use Facebook\WebDriver\WebDriverBy;

use Facebook\WebDriver\WebDriverElement;

// NOTE: no MOODLE_INTERNAL test here, this file may be required by behat before including /config.php.

require_once(__DIR__ . '/component_named_replacement.php');

require_once(__DIR__ . '/component_named_selector.php');

// Alias the Facebook\WebDriver\WebDriverKeys class to behat_keys for better b/c with the older Instaclick driver.

class_alias('Facebook\WebDriver\WebDriverKeys', 'behat_keys');

/**

 * A trait containing functionality used by the behat base context, and form fields.

 *

 * This trait should be used by the behat_base context, and behat form fields, and it should be paired with the

 * behat_session_interface interface.

 *

 * It should not be necessary to use this trait, and the behat_session_interface interface in normal circumstances.

 *

 * @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

 */

trait behat_session_trait {

    /**

     * Locates url, based on provided path.

     * Override to provide custom routing mechanism.

     *

     * @see Behat\MinkExtension\Context\MinkContext

     * @param string $path

     * @return string

     */

    protected function locate_path($path) {

        $starturl = rtrim($this->getMinkParameter('base_url'), '/') . '/';

        return 0 !== strpos($path, 'http') ? $starturl . ltrim($path, '/') : $path;

    }

    /**

     * Returns the first matching element.

     *

     * @link http://mink.behat.org/#traverse-the-page-selectors

     * @param string $selector The selector type (css, xpath, named...)

     * @param mixed $locator It depends on the $selector, can be the xpath, a name, a css locator...

     * @param Exception $exception Otherwise we throw exception with generic info

     * @param NodeElement $node Spins around certain DOM node instead of the whole page

     * @param int $timeout Forces a specific time out (in seconds).

     * @return NodeElement

     */

    protected function find($selector, $locator, $exception = false, $node = false, $timeout = false) {

        if ($selector === 'NodeElement' && is_a($locator, NodeElement::class)) {

            // Support a NodeElement being passed in for use in step chaining.

            return $locator;

        }

        // Returns the first match.

        $items = $this->find_all($selector, $locator, $exception, $node, $timeout);

        return count($items) ? reset($items) : null;

    }

    /**

     * Returns all matching elements.

     *

     * Adapter to Behat\Mink\Element\Element::findAll() using the spin() method.

     *

     * @link http://mink.behat.org/#traverse-the-page-selectors

     * @param string $selector The selector type (css, xpath, named...)

     * @param mixed $locator It depends on the $selector, can be the xpath, a name, a css locator...

     * @param Exception $exception Otherwise we throw expcetion with generic info

     * @param NodeElement $container Restrict the search to just children of the specified container

     * @param int $timeout Forces a specific time out (in seconds). If 0 is provided the default timeout will be applied.

     * @return array NodeElements list

     */

    protected function find_all($selector, $locator, $exception = false, $container = false, $timeout = false) {

        // Throw exception, so dev knows it is not supported.

        if ($selector === 'named') {

            $exception = 'Using the "named" selector is deprecated as of 3.1. '

                .' Use the "named_partial" or use the "named_exact" selector instead.';

            throw new ExpectationException($exception, $this->getSession());

        }

        // Generic info.

        if (!$exception) {

            // With named selectors we can be more specific.

            if (($selector == 'named_exact') || ($selector == 'named_partial')) {

                $exceptiontype = $locator[0];

                $exceptionlocator = $locator[1];

                // If we are in a @javascript session all contents would be displayed as HTML characters.

                if ($this->running_javascript()) {

                    $locator[1] = html_entity_decode($locator[1], ENT_NOQUOTES);

                }

            } else {

                $exceptiontype = $selector;

                $exceptionlocator = $locator;

            }

            $exception = new ElementNotFoundException($this->getSession(), $exceptiontype, null, $exceptionlocator);

        }

        // How much we will be waiting for the element to appear.

        if ($timeout === false) {

            $timeout = self::get_timeout();

            $microsleep = false;

        } else {

            // Spinning each 0.1 seconds if the timeout was forced as we understand

            // that is a special case and is good to refine the performance as much

            // as possible.

            $microsleep = true;

        }

        // Normalise the values in order to perform the search.

        [

            'selector' => $selector,

            'locator' => $locator,

            'container' => $container,

        ] = $this->normalise_selector($selector, $locator, $container ?: $this->getSession()->getPage());

        // Waits for the node to appear if it exists, otherwise will timeout and throw the provided exception.

        return $this->spin(

            function() use ($selector, $locator, $container) {

                return $container->findAll($selector, $locator);

            }, [], $timeout, $exception, $microsleep

        );

    }

    /**

     * Normalise the locator and selector.

     *

     * @param string $selector The type of thing to search

     * @param mixed $locator The locator value. Can be an array, but is more likely a string.

     * @param Element $container An optional container to search within

     * @return array The selector, locator, and container to search within

     */

    public function normalise_selector(string $selector, $locator, Element $container): array {

        // Check for specific transformations for this selector type.

        $transformfunction = "transform_find_for_{$selector}";

        if (method_exists('behat_selectors', $transformfunction)) {

            // A selector-specific transformation exists.

            // Perform initial transformation of the selector within the current container.

            [

                'selector' => $selector,

                'locator' => $locator,

                'container' => $container,

            ] = behat_selectors::{$transformfunction}($this, $locator, $container);

        }

        // Normalise the css and xpath selector types.

        if ('css_element' === $selector) {

            $selector = 'css';

        } else if ('xpath_element' === $selector) {

            $selector = 'xpath';

        }

        // Convert to a named selector where the selector type is not a known selector.

        $converttonamed = !$this->getSession()->getSelectorsHandler()->isSelectorRegistered($selector);

        $converttonamed = $converttonamed && 'xpath' !== $selector;

        if ($converttonamed) {

            if (behat_partial_named_selector::is_deprecated_selector($selector)) {

                if ($replacement = behat_partial_named_selector::get_deprecated_replacement($selector)) {

                    error_log("The '{$selector}' selector has been replaced with {$replacement}");

                    $selector = $replacement;

                }

            } else if (behat_exact_named_selector::is_deprecated_selector($selector)) {

                if ($replacement = behat_exact_named_selector::get_deprecated_replacement($selector)) {

                    error_log("The '{$selector}' selector has been replaced with {$replacement}");

                    $selector = $replacement;

                }

            }

            $allowedpartialselectors = behat_partial_named_selector::get_allowed_selectors();

            $allowedexactselectors = behat_exact_named_selector::get_allowed_selectors();

            if (isset($allowedpartialselectors[$selector])) {

                $locator = behat_selectors::normalise_named_selector($allowedpartialselectors[$selector], $locator);

                $selector = 'named_partial';

            } else if (isset($allowedexactselectors[$selector])) {

                $locator = behat_selectors::normalise_named_selector($allowedexactselectors[$selector], $locator);

                $selector = 'named_exact';

            } else {

                throw new ExpectationException("The '{$selector}' selector type is not registered.", $this->getSession()->getDriver());

            }

        }

        return [

            'selector' => $selector,

            'locator' => $locator,

            'container' => $container,

        ];

    }

    /**

     * Get a description of the selector and locator to use in an exception message.

     *

     * @param string $selector The type of locator

     * @param mixed $locator The locator text

     * @return string

     */

    protected function get_selector_description(string $selector, $locator): string {

        if ($selector === 'NodeElement') {

            $description = $locator->getText();

            return "'{$description}' {$selector}";

        }

        return "'{$locator}' {$selector}";

    }

    /**

     * Send key presses straight to the currently active element.

     *

     * The `$keys` array contains a list of key values to send to the session as defined in the WebDriver and JsonWire

     * specifications:

     * - JsonWire: https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#sessionsessionidkeys

     * - W3C WebDriver: https://www.w3.org/TR/webdriver/#keyboard-actions

     *

     * This may be a combination of typable characters, modifier keys, and other supported keypoints.

     *

     * The NULL_KEY should be used to release modifier keys. If the NULL_KEY is not used then modifier keys will remain

     * in the pressed state.

     *

     * Example usage:

     *

     *      behat_base::type_keys($this->getSession(), [behat_keys::SHIFT, behat_keys::TAB, behat_keys::NULL_KEY]);

     *      behat_base::type_keys($this->getSession(), [behat_keys::ENTER, behat_keys::NULL_KEY]);

     *      behat_base::type_keys($this->getSession(), [behat_keys::ESCAPE, behat_keys::NULL_KEY]);

     *

     * It can also be used to send text input, for example:

     *

     *      behat_base::type_keys(

     *          $this->getSession(),

     *          ['D', 'o', ' ', 'y', 'o', 'u', ' ', 'p', 'l', 'a' 'y', ' ', 'G', 'o', '?', behat_base::NULL_KEY]

     *      );

     *

     *

     * Please note: This function does not use the element/sendKeys variants but sends keys straight to the browser.

     *

     * @param Session $session

     * @param string[] $keys

     */

    public static function type_keys(Session $session, array $keys): void {

        $session->getDriver()->getWebDriver()->getKeyboard()->sendKeys($keys);

    }

    /**

     * Finds DOM nodes in the page using named selectors.

     *

     * The point of using this method instead of Mink ones is the spin

     * method of behat_base::find() that looks for the element until it

     * is available or it timeouts, this avoids the false failures received

     * when selenium tries to execute commands on elements that are not

     * ready to be used.

     *

     * All steps that requires elements to be available before interact with

     * them should use one of the find* methods.

     *

     * The methods calls requires a {'find_' . $elementtype}($locator)

     * format, like find_link($locator), find_select($locator),

     * find_button($locator)...

     *

     * @link http://mink.behat.org/#named-selectors

     * @throws coding_exception

     * @param string $name The name of the called method

     * @param mixed $arguments

     * @return NodeElement

     */

    public function __call($name, $arguments) {

        if (substr($name, 0, 5) === 'find_') {

            return call_user_func_array([$this, 'find'], array_merge(

                [substr($name, 5)],

                $arguments

            ));

        }

        throw new coding_exception("The '{$name}' method does not exist");

    }

    /**

     * Escapes the double quote character.

     *

     * Double quote is the argument delimiter, it can be escaped

     * with a backslash, but we auto-remove this backslashes

     * before the step execution, this method is useful when using

     * arguments as arguments for other steps.

     *

     * @param string $string

     * @return string

     */

    public function escape($string) {

        return str_replace('"', '\"', $string);

    }

    /**

     * Executes the passed closure until returns true or time outs.

     *

     * In most cases the document.readyState === 'complete' will be enough, but sometimes JS

     * requires more time to be completely loaded or an element to be visible or whatever is required to

     * perform some action on an element; this method receives a closure which should contain the

     * required statements to ensure the step definition actions and assertions have all their needs

     * satisfied and executes it until they are satisfied or it timeouts. Redirects the return of the

     * closure to the caller.

     *

     * The closures requirements to work well with this spin method are:

     * - Must return false, null or '' if something goes wrong

     * - Must return something != false if finishes as expected, this will be the (mixed) value

     * returned by spin()

     *

     * The arguments of the closure are mixed, use $args depending on your needs.

     *

     * You can provide an exception to give more accurate feedback to tests writers, otherwise the

     * closure exception will be used, but you must provide an exception if the closure does not throw

     * an exception.

     *

     * @throws Exception If it timeouts without receiving something != false from the closure

     * @param callable $lambda The function to execute or an array passed to call_user_func (maps to a class method)

     * @param mixed $args Arguments to pass to the closure

     * @param int $timeout Timeout in seconds

     * @param Exception $exception The exception to throw in case it time outs.

     * @param bool $microsleep If set to true it'll sleep micro seconds rather than seconds.

     * @return mixed The value returned by the closure

     */

    protected function spin($lambda, $args = false, $timeout = false, $exception = false, $microsleep = false) {

        // Using default timeout which is pretty high.

        if ($timeout === false) {

            $timeout = self::get_timeout();

        }

        $start = microtime(true);

        $end = $start + $timeout;

        do {

            // We catch the exception thrown by the step definition to execute it again.

            try {

                // We don't check with !== because most of the time closures will return

                // direct Behat methods returns and we are not sure it will be always (bool)false

                // if it just runs the behat method without returning anything $return == null.

                if ($return = call_user_func($lambda, $this, $args)) {

                    return $return;

                }

            } catch (Exception $e) {

                // We would use the first closure exception if no exception has been provided.

                if (!$exception) {

                    $exception = $e;

                }

            }

            if (!$this->running_javascript()) {

                break;

            }

            usleep(100000);

        } while (microtime(true) < $end);

        // Using coding_exception as is a development issue if no exception has been provided.

        if (!$exception) {

            $exception = new coding_exception('spin method requires an exception if the callback does not throw an exception');

        }

        // Throwing exception to the user.

        throw $exception;

    }

    /**

     * Gets a NodeElement based on the locator and selector type received as argument from steps definitions.

     *

     * Use behat_base::get_text_selector_node() for text-based selectors.

     *

     * @throws ElementNotFoundException Thrown by behat_base::find

     * @param string $selectortype

     * @param string $element

     * @return NodeElement

     */

    protected function get_selected_node($selectortype, $element) {

        return $this->find($selectortype, $element);

    }

    /**

     * Gets a NodeElement based on the locator and selector type received as argument from steps definitions.

     *

     * @throws ElementNotFoundException Thrown by behat_base::find

     * @param string $selectortype

     * @param string $element

     * @return NodeElement

     */

    protected function get_text_selector_node($selectortype, $element) {

        // Getting Mink selector and locator.

        list($selector, $locator) = $this->transform_text_selector($selectortype, $element);

        // Returns the NodeElement.

        return $this->find($selector, $locator);

    }

    /**

     * Gets the requested element inside the specified container.

     *

     * @throws ElementNotFoundException Thrown by behat_base::find

     * @param mixed $selectortype The element selector type.

     * @param mixed $element The element locator.

     * @param mixed $containerselectortype The container selector type.

     * @param mixed $containerelement The container locator.

     * @return NodeElement

     */

    protected function get_node_in_container($selectortype, $element, $containerselectortype, $containerelement) {

        if ($containerselectortype === 'NodeElement' && is_a($containerelement, NodeElement::class)) {

            // Support a NodeElement being passed in for use in step chaining.

            $containernode = $containerelement;

        } else {

            // Gets the container, it will always be text based.

            $containernode = $this->get_text_selector_node($containerselectortype, $containerelement);

        }

        $locatorexceptionmsg = $element . '" in the "' . $this->get_selector_description($containerselectortype, $containerelement);

        $exception = new ElementNotFoundException($this->getSession(), $selectortype, null, $locatorexceptionmsg);

        return $this->find($selectortype, $element, $exception, $containernode);

    }

    /**

     * Transforms from step definition's argument style to Mink format.

     *

     * Mink has 3 different selectors css, xpath and named, where named

     * selectors includes link, button, field... to simplify and group multiple

     * steps in one we use the same interface, considering all link, buttons...

     * at the same level as css selectors and xpath; this method makes the

     * conversion from the arguments received by the steps to the selectors and locators

     * required to interact with Mink.

     *

     * @throws ExpectationException

     * @param string $selectortype It can be css, xpath or any of the named selectors.

     * @param string $element The locator (or string) we are looking for.

     * @return array Contains the selector and the locator expected by Mink.

     */

    protected function transform_selector($selectortype, $element) {

        // Here we don't know if an allowed text selector is being used.

        $selectors = behat_selectors::get_allowed_selectors();

        if (!isset($selectors[$selectortype])) {

            throw new ExpectationException('The "' . $selectortype . '" selector type does not exist', $this->getSession());

        }

        [

            'selector' => $selector,

            'locator' => $locator,

        ] = $this->normalise_selector($selectortype, $element, $this->getSession()->getPage());

        return [$selector, $locator];

    }

    /**

     * Transforms from step definition's argument style to Mink format.

     *

     * Delegates all the process to behat_base::transform_selector() checking

     * the provided $selectortype.

     *

     * @throws ExpectationException

     * @param string $selectortype It can be css, xpath or any of the named selectors.

     * @param string $element The locator (or string) we are looking for.

     * @return array Contains the selector and the locator expected by Mink.

     */

    protected function transform_text_selector($selectortype, $element) {

        $selectors = behat_selectors::get_allowed_text_selectors();

        if (empty($selectors[$selectortype])) {

            throw new ExpectationException('The "' . $selectortype . '" selector can not be used to select text nodes', $this->getSession());

        }

        return $this->transform_selector($selectortype, $element);

    }

    /**

     * Whether Javascript is available in the current Session.

     *

     * @return boolean

     */

    protected function running_javascript() {

        return self::running_javascript_in_session($this->getSession());

    }

    /**

     * Require that javascript be available in the current Session.

     *

     * @param null|string $message An additional information message to show when JS is not available

     * @throws DriverException

     */

    protected function require_javascript(?string $message = null) {

        return self::require_javascript_in_session($this->getSession(), $message);

    }

    /**

     * Whether Javascript is available in the specified Session.

     *

     * @param Session $session

     * @return boolean

     */

    protected static function running_javascript_in_session(Session $session): bool {

        return get_class($session->getDriver()) !== 'Behat\Mink\Driver\BrowserKitDriver';

    }

    /**

     * Require that javascript be available for the specified Session.

     *

     * @param Session $session

     * @param null|string $message An additional information message to show when JS is not available

     * @throws DriverException

     */

    protected static function require_javascript_in_session(Session $session, ?string $message = null): void {

        if (self::running_javascript_in_session($session)) {

            return;

        }

        $error = "Javascript is required for this step.";

        if ($message) {

            $error = "{$error} {$message}";

        }

        throw new DriverException($error);

    }

    /**

     * Checks if the current page is part of the mobile app.

     *

     * @return bool True if it's in the app

     */

    protected function is_in_app(): bool {

        // Cannot be in the app if there's no @app tag on scenario.

        if (!$this->has_tag('app')) {

            return false;

        }

        // Check on page to see if it's an app page. Safest way is to look for added JavaScript.

        return $this->evaluate_script('return typeof window.behat') === 'object';

    }

    /**

     * Spins around an element until it exists

     *

     * @throws ExpectationException

     * @param string $locator

     * @param string $selectortype

     * @return void

     */

    protected function ensure_element_exists($locator, $selectortype) {

        // Exception if it timesout and the element is still there.

        $msg = "The '{$locator}' element does not exist and should";

        $exception = new ExpectationException($msg, $this->getSession());

        // Normalise the values in order to perform the search.

        [

            'selector' => $selector,

            'locator' => $locator,

            'container' => $container,

        ] = $this->normalise_selector($selectortype, $locator, $this->getSession()->getPage());

        // It will stop spinning once the find() method returns true.

        $this->spin(

            function() use ($selector, $locator, $container) {

                if ($container->find($selector, $locator)) {

                    return true;

                }

                return false;

            },

            [],

            self::get_extended_timeout(),

            $exception,

            true

        );

    }

    /**

     * Spins until the element does not exist

     *

     * @throws ExpectationException

     * @param string $locator

     * @param string $selectortype

     * @return void

     */

    protected function ensure_element_does_not_exist($locator, $selectortype) {

        // Exception if it timesout and the element is still there.

        $msg = "The '{$locator}' element exists and should not exist";

        $exception = new ExpectationException($msg, $this->getSession());

        // Normalise the values in order to perform the search.

        [

            'selector' => $selector,

            'locator' => $locator,

            'container' => $container,

        ] = $this->normalise_selector($selectortype, $locator, $this->getSession()->getPage());

        // It will stop spinning once the find() method returns false.

        $this->spin(

            function() use ($selector, $locator, $container) {

                if ($container->find($selector, $locator)) {

                    return false;

                }

                return true;

            },

            // Note: We cannot use $this because the find will then be $this->find(), which leads us to a nested spin().

            // We cannot nest spins because the outer spin times out before the inner spin completes.

            [],

            self::get_extended_timeout(),

            $exception,

            true

        );

    }

    /**

     * Ensures that the provided node is visible and we can interact with it.

     *

     * @throws ExpectationException

     * @param NodeElement $node

     * @return void Throws an exception if it times out without the element being visible

     */

    protected function ensure_node_is_visible($node) {

        if (!$this->running_javascript()) {

            return;

        }

        // Exception if it timesout and the element is still there.

        $msg = 'The "' . $node->getXPath() . '" xpath node is not visible and it should be visible';

        $exception = new ExpectationException($msg, $this->getSession());

        // It will stop spinning once the isVisible() method returns true.

        $this->spin(

            function($context, $args) {

                if ($args->isVisible()) {

                    return true;

                }

                return false;

            },

            $node,

            self::get_extended_timeout(),

            $exception,

            true

        );

    }

    /**

     * Ensures that the provided node has a attribute value set. This step can be used to check if specific

     * JS has finished modifying the node.

     *

     * @throws ExpectationException

     * @param NodeElement $node

     * @param string $attribute attribute name

     * @param string $attributevalue attribute value to check.

     * @return void Throws an exception if it times out without the element being visible

     */

    protected function ensure_node_attribute_is_set($node, $attribute, $attributevalue) {

        if (!$this->running_javascript()) {

            return;

        }

        // Exception if it timesout and the element is still there.

        $msg = 'The "' . $node->getXPath() . '" xpath node is not visible and it should be visible';

        $exception = new ExpectationException($msg, $this->getSession());

        // It will stop spinning once the $args[1]) == $args[2], and method returns true.

        $this->spin(

            function($context, $args) {

                if ($args[0]->getAttribute($args[1]) == $args[2]) {

                    return true;

                }

                return false;

            },

            array($node, $attribute, $attributevalue),

            self::get_extended_timeout(),

            $exception,

            true

        );

    }

    /**

     * Ensures that the provided element is visible and we can interact with it.

     *

     * Returns the node in case other actions are interested in using it.

     *

     * @throws ExpectationException

     * @param string $element

     * @param string $selectortype

     * @return NodeElement Throws an exception if it times out without being visible

     */

    protected function ensure_element_is_visible($element, $selectortype) {

        if (!$this->running_javascript()) {

            return;

        }

        $node = $this->get_selected_node($selectortype, $element);

        $this->ensure_node_is_visible($node);

        return $node;

    }

    /**

     * Checks if the current scenario, or its feature, has a specified tag.

     *

     * @param string $tag Tag to check

     * @return bool True if the tag exists in scenario or feature

     */

    public function has_tag(string $tag): bool {

        return array_key_exists($tag, behat_hooks::get_tags_for_scenario());

    }

    /**

     * Change browser window size.

     *   - mobile: 425x750

     *   - tablet: 768x1024

     *   - small: 1024x768

     *   - medium: 1366x768

     *   - large: 2560x1600

     *

     * @param string $windowsize size of window.

     * @param bool $viewport If true, changes viewport rather than window size

     * @throws ExpectationException

     */

    protected function resize_window($windowsize, $viewport = false) {

        global $CFG;

        // Non JS don't support resize window.

        if (!$this->running_javascript()) {

            return;

        }

        switch ($windowsize) {

            case "mobile":

                $width = 425;

                $height = 750;

                break;

            case "tablet":

                $width = 768;

                $height = 1024;

                break;

            case "small":

                $width = 1024;

                $height = 768;

                break;

            case "medium":

                $width = 1366;

                $height = 768;

                break;

            case "large":

                $width = 2560;

                $height = 1600;

                break;

            default:

                preg_match('/^(\d+x\d+)$/', $windowsize, $matches);

                if (empty($matches) || (count($matches) != 2)) {

                    throw new ExpectationException("Invalid screen size, can't resize", $this->getSession());

                }

                $size = explode('x', $windowsize);

                $width = (int) $size[0];

                $height = (int) $size[1];

        }

        if (isset($CFG->behat_window_size_modifier) && is_numeric($CFG->behat_window_size_modifier)) {

            $width *= $CFG->behat_window_size_modifier;

            $height *= $CFG->behat_window_size_modifier;

        }

        if ($viewport) {

            // When setting viewport size, we set it so that the document width will be exactly

            // as specified, assuming that there is a vertical scrollbar. (In cases where there is

            // no scrollbar it will be slightly wider. We presume this is rare and predictable.)

            // The window inner height will be as specified, which means the available viewport will

            // actually be smaller if there is a horizontal scrollbar. We assume that horizontal

            // scrollbars are rare so this doesn't matter.

            $js = <<<EOF

return (function() {

    var before = document.body.style.overflowY;

    document.body.style.overflowY = "scroll";

    var result = {};

    result.x = window.outerWidth - document.body.offsetWidth;

    result.y = window.outerHeight - window.innerHeight;

    document.body.style.overflowY = before;

    return result;

})();

EOF;

            $offset = $this->evaluate_script($js);

            $width += $offset['x'];

            $height += $offset['y'];

        }

        $this->getSession()->getDriver()->resizeWindow($width, $height);

    }

    /**

     * Waits for all the JS to be loaded.

     *

     * @return  bool Whether any JS is still pending completion.

     */

    public function wait_for_pending_js() {

        return static::wait_for_pending_js_in_session($this->getSession());

    }

    /**

     * Waits for all the JS to be loaded.

     *

     * @param   Session $session The Mink Session where JS can be run

     * @return  bool Whether any JS is still pending completion.

     */

    public static function wait_for_pending_js_in_session(Session $session) {

        if (!self::running_javascript_in_session($session)) {

            // JS is not available therefore there is nothing to wait for.

            return false;

        }

        // We don't use behat_base::spin() here as we don't want to end up with an exception

        // if the page & JSs don't finish loading properly.

        for ($i = 0; $i < self::get_extended_timeout() * 10; $i++) {

            $pending = '';

            try {

                $jscode = trim(preg_replace('/\s+/', ' ', '

                    return (function() {

                        if (document.readyState !== "complete") {

                            return "incomplete";

                        }

                        if (typeof M !== "object" || typeof M.util !== "object" || typeof M.util.pending_js === "undefined") {

                            return "";

                        }

                        return M.util.pending_js.join(":");

                    })()'));

                $pending = self::evaluate_script_in_session($session, $jscode);

            } catch (NoSuchWindowException $nsw) {

                // We catch an exception here, in case we just closed the window we were interacting with.

                // No javascript is running if there is no window right?

                $pending = '';

            } catch (UnknownError $e) {

                // M is not defined when the window or the frame don't exist anymore.

                if (strstr($e->getMessage(), 'M is not defined') != false) {

                    $pending = '';

                }

            }

            // If there are no pending JS we stop waiting.

            if ($pending === '') {

                return true;

            }

            // 0.1 seconds.

            usleep(100000);

        }

        // Timeout waiting for JS to complete. It will be caught and forwarded to behat_hooks::i_look_for_exceptions().

        // It is unlikely that Javascript code of a page or an AJAX request needs more than get_extended_timeout() seconds

        // to be loaded, although when pages contains Javascript errors M.util.js_complete() can not be executed, so the

        // number of JS pending code and JS completed code will not match and we will reach this point.

        throw new \Exception('Javascript code and/or AJAX requests are not ready after ' .

                self::get_extended_timeout() .

                ' seconds. There is a Javascript error or the code is extremely slow (' . $pending .

                '). If you are using a slow machine, consider setting $CFG->behat_increasetimeout.');

    }

    /**

     * Internal step definition to find exceptions, debugging() messages and PHP debug messages.

     *

     * Part of behat_hooks class as is part of the testing framework, is auto-executed

     * after each step so no features will splicitly use it.

     *

     * @throws Exception Unknown type, depending on what we caught in the hook or basic \Exception.

     * @see Moodle\BehatExtension\Tester\MoodleStepTester

     */

    public function look_for_exceptions() {

        // Wrap in try in case we were interacting with a closed window.

        try {

            // Exceptions.

            $exceptionsxpath = "//div[@data-rel='fatalerror']";

            // Debugging messages.

            $debuggingxpath = "//div[@data-rel='debugging']";

            // PHP debug messages.

            $phperrorxpath = "//div[@data-rel='phpdebugmessage']";

            // Any other backtrace.

            $othersxpath = "(//*[contains(., ': call to ')])[1]";

            $xpaths = array($exceptionsxpath, $debuggingxpath, $phperrorxpath, $othersxpath);

            $joinedxpath = implode(' | ', $xpaths);

            // Joined xpath expression. Most of the time there will be no exceptions, so this pre-check

            // is faster than to send the 4 xpath queries for each step.

            if (!$this->getSession()->getDriver()->find($joinedxpath)) {

                // Check if we have recorded any errors in driver process.

                $phperrors = behat_get_shutdown_process_errors();

                if (!empty($phperrors)) {

                    foreach ($phperrors as $error) {

                        $errnostring = behat_get_error_string($error['type']);

                        $msgs[] = $errnostring . ": " .$error['message'] . " at " . $error['file'] . ": " . $error['line'];

                    }

                    $msg = "PHP errors found:\n" . implode("\n", $msgs);

                    throw new \Exception(htmlentities($msg, ENT_COMPAT));

                }

                return;

            }

            // Exceptions.

            if ($errormsg = $this->getSession()->getPage()->find('xpath', $exceptionsxpath)) {

                // Getting the debugging info and the backtrace.

                $errorinfoboxes = $this->getSession()->getPage()->findAll('css', 'div.alert-error');

                // If errorinfoboxes is empty, try find alert-danger (bootstrap4) class.

                if (empty($errorinfoboxes)) {

                    $errorinfoboxes = $this->getSession()->getPage()->findAll('css', 'div.alert-danger');

                }

                // If errorinfoboxes is empty, try find notifytiny (original) class.

                if (empty($errorinfoboxes)) {

                    $errorinfoboxes = $this->getSession()->getPage()->findAll('css', 'div.notifytiny');

                }

                // If errorinfoboxes is empty, try find ajax/JS exception in dialogue.

                if (empty($errorinfoboxes)) {

                    $errorinfoboxes = $this->getSession()->getPage()->findAll('css', 'div.moodle-exception-message');

                    // If ajax/JS exception.

                    if ($errorinfoboxes) {

                        $errorinfo = $this->get_debug_text($errorinfoboxes[0]->getHtml());

                    }

                } else {

                    $errorinfo = implode("\n", [

                        $this->get_debug_text($errorinfoboxes[0]->getHtml()),

                        $this->get_debug_text($errorinfoboxes[1]->getHtml()),

                        html_to_text($errorinfoboxes[2]->find('css', 'ul')->getHtml()),

                    ]);

                }

                $msg = "Moodle exception: " . $errormsg->getText() . "\n" . $errorinfo;

                throw new \Exception(html_entity_decode($msg, ENT_COMPAT));

            }

            // Debugging messages.

            if ($debuggingmessages = $this->getSession()->getPage()->findAll('xpath', $debuggingxpath)) {

                $msgs = array();

                foreach ($debuggingmessages as $debuggingmessage) {

                    $msgs[] = $this->get_debug_text($debuggingmessage->getHtml());

                }

                $msg = "debugging() message/s found:\n" . implode("\n", $msgs);

                throw new \Exception(html_entity_decode($msg, ENT_COMPAT));

            }

            // PHP debug messages.

            if ($phpmessages = $this->getSession()->getPage()->findAll('xpath', $phperrorxpath)) {

                $msgs = array();

                foreach ($phpmessages as $phpmessage) {

                    $msgs[] = $this->get_debug_text($phpmessage->getHtml());

                }

                $msg = "PHP debug message/s found:\n" . implode("\n", $msgs);

                throw new \Exception(html_entity_decode($msg, ENT_COMPAT));

            }

            // Any other backtrace.

            // First looking through xpath as it is faster than get and parse the whole page contents,

            // we get the contents and look for matches once we found something to suspect that there is a backtrace.

            if ($this->getSession()->getDriver()->find($othersxpath)) {

                $backtracespattern = '/(line [0-9]* of [^:]*: call to [\->&;:a-zA-Z_\x7f-\xff][\->&;:a-zA-Z0-9_\x7f-\xff]*)/';

                if (preg_match_all($backtracespattern, $this->getSession()->getPage()->getContent(), $backtraces)) {

                    $msgs = array();

                    foreach ($backtraces[0] as $backtrace) {

                        $msgs[] = $backtrace . '()';

                    }

                    $msg = "Other backtraces found:\n" . implode("\n", $msgs);

                    throw new \Exception(htmlentities($msg, ENT_COMPAT));

                }

            }