diff --git a/lib/behat/classes/util.php b/lib/behat/classes/util.php
index c8504fe3b9f..57e56b0f927 100644
--- a/lib/behat/classes/util.php
+++ b/lib/behat/classes/util.php
@@ -85,6 +85,10 @@ class behat_util extends testing_util {
 
         install_cli_database($options, false);
 
+        // We need to keep the installed dataroot filedir files.
+        // So each time we reset the dataroot before running a test, the default files are still installed.
+        self::save_original_data_files();
+
         $frontpagesummary = new admin_setting_special_frontpagedesc();
         $frontpagesummary->write_setting(self::BEHATSITENAME);
 
diff --git a/lib/phpunit/classes/util.php b/lib/phpunit/classes/util.php
old mode 100644
new mode 100755
index 28d7ea5dffa..ed8d632f433
--- a/lib/phpunit/classes/util.php
+++ b/lib/phpunit/classes/util.php
@@ -384,6 +384,10 @@ class phpunit_util extends testing_util {
 
         install_cli_database($options, false);
 
+        // We need to keep the installed dataroot filedir files.
+        // So each time we reset the dataroot before running a test, the default files are still installed.
+        self::save_original_data_files();
+
         // install timezone info
         $timezones = get_records_csv($CFG->libdir.'/timezone.txt', 'timezone');
         update_timezone_records($timezones);
diff --git a/lib/testing/classes/util.php b/lib/testing/classes/util.php
old mode 100644
new mode 100755
index 41a4243318a..deec3100cd4
--- a/lib/testing/classes/util.php
+++ b/lib/testing/classes/util.php
@@ -34,6 +34,11 @@
  */
 abstract class testing_util {
 
+    /**
+     * @var string dataroot (likely to be $CFG->dataroot).
+     */
+    private static $dataroot = null;
+
     /**
      * @var int last value of db writes counter, used for db resetting
      */
@@ -64,6 +69,53 @@ abstract class testing_util {
      */
     protected static $sequencenames = null;
 
+    /**
+     * @var string name of the json file where we store the list of dataroot files to not reset during reset_dataroot.
+     */
+    private static $originaldatafilesjson = 'originaldatafiles.json';
+
+    /**
+     * @var boolean set to true once $originaldatafilesjson file is created.
+     */
+    private static $originaldatafilesjsonadded = false;
+
+    /**
+     * Return the name of the JSON file containing the init filenames.
+     *
+     * @static
+     * @return string
+     */
+    public static function get_originaldatafilesjson() {
+        return self::$originaldatafilesjson;
+    }
+
+    /**
+     * Return the dataroot. It's useful when mocking the dataroot when unit testing this class itself.
+     *
+     * @static
+     * @return string the dataroot.
+     */
+    public static function get_dataroot() {
+        global $CFG;
+
+        //  By default it's the test framework dataroot.
+        if (empty(self::$dataroot)) {
+            self::$dataroot = $CFG->dataroot;
+        }
+
+        return self::$dataroot;
+    }
+
+    /**
+     * Set the dataroot. It's useful when mocking the dataroot when unit testing this class itself.
+     *
+     * @param string $dataroot the dataroot of the test framework.
+     * @static
+     */
+    public static function set_dataroot($dataroot) {
+        self::$dataroot = $dataroot;
+    }
+
     /**
      * Returns the testing framework name
      * @static
@@ -99,7 +151,7 @@ abstract class testing_util {
 
         $framework = self::get_framework();
 
-        if (!file_exists($CFG->dataroot . '/' . $framework . 'testdir.txt')) {
+        if (!file_exists(self::get_dataroot() . '/' . $framework . 'testdir.txt')) {
             // this is already tested in bootstrap script,
             // but anyway presence of this file means the dataroot is for testing
             return false;
@@ -128,7 +180,7 @@ abstract class testing_util {
 
         $framework = self::get_framework();
 
-        $datarootpath = $CFG->dataroot . '/' . $framework;
+        $datarootpath = self::get_dataroot() . '/' . $framework;
         if (!file_exists($datarootpath . '/tabledata.ser') or !file_exists($datarootpath . '/tablestructure.ser')) {
             return false;
         }
@@ -178,12 +230,12 @@ abstract class testing_util {
             }
         }
         $data = serialize($data);
-        $datafile = $CFG->dataroot . '/' . $framework . '/tabledata.ser';
+        $datafile = self::get_dataroot() . '/' . $framework . '/tabledata.ser';
         file_put_contents($datafile, $data);
         testing_fix_file_permissions($datafile);
 
         $structure = serialize($structure);
-        $structurefile = $CFG->dataroot . '/' . $framework . '/tablestructure.ser';
+        $structurefile = self::get_dataroot() . '/' . $framework . '/tablestructure.ser';
         file_put_contents($structurefile, $structure);
         testing_fix_file_permissions($structurefile);
     }
@@ -201,7 +253,7 @@ abstract class testing_util {
         set_config($framework . 'test', $hash);
 
         // hash all plugin versions - helps with very fast detection of db structure changes
-        $hashfile = $CFG->dataroot . '/' . $framework . '/versionshash.txt';
+        $hashfile = self::get_dataroot() . '/' . $framework . '/versionshash.txt';
         file_put_contents($hashfile, $hash);
         testing_fix_file_permissions($hashfile);
     }
@@ -216,7 +268,7 @@ abstract class testing_util {
 
         $framework = self::get_framework();
 
-        $datafile = $CFG->dataroot . '/' . $framework . '/tabledata.ser';
+        $datafile = self::get_dataroot() . '/' . $framework . '/tabledata.ser';
         if (!file_exists($datafile)) {
             // Not initialised yet.
             return array();
@@ -244,7 +296,7 @@ abstract class testing_util {
 
         $framework = self::get_framework();
 
-        $structurefile = $CFG->dataroot . '/' . $framework . '/tablestructure.ser';
+        $structurefile = self::get_dataroot() . '/' . $framework . '/tablestructure.ser';
         if (!file_exists($structurefile)) {
             // Not initialised yet.
             return array();
@@ -584,18 +636,39 @@ abstract class testing_util {
 
         $childclassname = self::get_framework() . '_util';
 
-        $handle = opendir($CFG->dataroot);
+        // Do not delete automatically installed files.
+        self::skip_original_data_files($childclassname);
+
+        // Clean up the dataroot folder.
+        $handle = opendir(self::get_dataroot());
         while (false !== ($item = readdir($handle))) {
             if (in_array($item, $childclassname::$datarootskiponreset)) {
                 continue;
             }
-            if (is_dir("$CFG->dataroot/$item")) {
-                remove_dir("$CFG->dataroot/$item", false);
+            if (is_dir(self::get_dataroot()."/$item")) {
+                remove_dir(self::get_dataroot()."/$item", false);
             } else {
-                unlink("$CFG->dataroot/$item");
+                unlink(self::get_dataroot()."/$item");
             }
         }
         closedir($handle);
+
+        // Clean up the dataroot/filedir folder.
+        if (file_exists(self::get_dataroot() . '/filedir')) {
+            $handle = opendir(self::get_dataroot() . '/filedir');
+            while (false !== ($item = readdir($handle))) {
+                if (in_array('filedir/' . $item, $childclassname::$datarootskiponreset)) {
+                    continue;
+                }
+                if (is_dir(self::get_dataroot()."/filedir/$item")) {
+                    remove_dir(self::get_dataroot()."/filedir/$item", false);
+                } else {
+                    unlink(self::get_dataroot()."/filedir/$item");
+                }
+            }
+            closedir($handle);
+        }
+
         make_temp_directory('');
         make_cache_directory('');
         make_localcache_directory('');
@@ -725,17 +798,83 @@ abstract class testing_util {
         $framework = self::get_framework();
         $childclassname = $framework . '_util';
 
-        $files = scandir($CFG->dataroot . '/' . $framework);
+        $files = scandir(self::get_dataroot() . '/'  . $framework);
         foreach ($files as $file) {
             if (in_array($file, $childclassname::$datarootskipondrop)) {
                 continue;
             }
-            $path = $CFG->dataroot . '/' . $framework . '/' . $file;
+            $path = self::get_dataroot() . '/' . $framework . '/' . $file;
             if (is_dir($path)) {
                 remove_dir($path, false);
             } else {
                 unlink($path);
             }
         }
+
+        $jsonfilepath = self::get_dataroot() . '/' . self::$originaldatafilesjson;
+        if (file_exists($jsonfilepath)) {
+            // Delete the json file.
+            unlink($jsonfilepath);
+            // Delete the dataroot filedir.
+            remove_dir(self::get_dataroot() . '/filedir', false);
+        }
+    }
+
+    /**
+     * Skip the original dataroot files to not been reset.
+     *
+     * @static
+     * @param string $utilclassname the util class name..
+     */
+    protected static function skip_original_data_files($utilclassname) {
+        $jsonfilepath = self::get_dataroot() . '/' . self::$originaldatafilesjson;
+        if (file_exists($jsonfilepath)) {
+
+            $listfiles = file_get_contents($jsonfilepath);
+
+            // Mark each files as to not be reset.
+            if (!empty($listfiles) && !self::$originaldatafilesjsonadded) {
+                $originaldatarootfiles = json_decode($listfiles);
+                // Keep the json file. Only drop_dataroot() should delete it.
+                $originaldatarootfiles[] = self::$originaldatafilesjson;
+                $utilclassname::$datarootskiponreset = array_merge($utilclassname::$datarootskiponreset,
+                    $originaldatarootfiles);
+                self::$originaldatafilesjsonadded = true;
+            }
+        }
+    }
+
+    /**
+     * Save the list of the original dataroot files into a json file.
+     */
+    protected static function save_original_data_files() {
+        global $CFG;
+
+        $jsonfilepath = self::get_dataroot() . '/' . self::$originaldatafilesjson;
+
+        // Save the original dataroot files if not done (only executed the first time).
+        if (!file_exists($jsonfilepath)) {
+
+            $listfiles = array();
+            $listfiles[] = 'filedir/.';
+            $listfiles[] = 'filedir/..';
+
+            $filedir = self::get_dataroot() . '/filedir';
+            if (file_exists($filedir)) {
+                $directory = new RecursiveDirectoryIterator($filedir);
+                foreach (new RecursiveIteratorIterator($directory) as $file) {
+                    if ($file->isDir()) {
+                        $listfiles[] = substr($file->getPath(), strlen(self::get_dataroot() . '/'));
+                    } else {
+                        $listfiles[] = substr($file->getPathName(), strlen(self::get_dataroot() . '/'));
+                    }
+                }
+            }
+
+            // Save the file list in a JSON file.
+            $fp = fopen($jsonfilepath, 'w');
+            fwrite($fp, json_encode($listfiles));
+            fclose($fp);
+        }
     }
 }