MDL-66568 behat: Reset theme CSS between scenarios

lib/behat/classes/util.php

@@ -427,6 +427,37 @@ class behat_util extends testing_util {
         initialise_cfg();
     }
 
+    /**
+     * Restore theme CSS stored during behat setup.
+     */
+    public static function restore_saved_themes(): void {
+        global $CFG;
+
+        $themerev = theme_get_revision();
+
+        $framework = self::get_framework();
+        $storageroot = self::get_dataroot() . "/{$framework}/themedata";
+        $themenames = array_keys(\core_component::get_plugin_list('theme'));
+        $directions = ['ltr', 'rtl'];
+
+        $themeconfigs = array_map(function($themename) {
+            return \theme_config::load($themename);
+        }, $themenames);
+
+        foreach ($themeconfigs as $themeconfig) {
+            $themename = $themeconfig->name;
+            $themesubrev = theme_get_sub_revision_for_theme($themename);
+
+            $dirname = "{$storageroot}/{$themename}";
+            foreach ($directions as $direction) {
+                $cssfile = "{$dirname}/{$direction}.css";
+                if (file_exists($cssfile)) {
+                    $themeconfig->set_css_content_cache(file_get_contents($cssfile));
+                }
+            }
+        }
+    }
+
     /**
      * Pause execution immediately.
      *

lib/tests/behat/behat_hooks.php

@@ -367,6 +367,16 @@ class behat_hooks extends behat_base {
         behat_util::reset_all_data();
         error_reporting($errorlevel);
 
+        if ($this->running_javascript()) {
+            // Fetch the user agent.
+            // This isused to choose between the SVG/Non-SVG versions of themes.
+            $useragent = $this->getSession()->evaluateScript('return navigator.userAgent;');
+            \core_useragent::instance(true, $useragent);
+
+            // Restore the saved themes.
+            behat_util::restore_saved_themes();
+        }
+
         // Assign valid data to admin user (some generator-related code needs a valid user).
         $user = $DB->get_record('user', array('username' => 'admin'));
         \core\session\manager::set_user($user);