diff --git a/lib/ddl/tests/ddl_test.php b/lib/ddl/tests/ddl_test.php
index 9f7385a6a4a..9c7cf43ff5f 100644
--- a/lib/ddl/tests/ddl_test.php
+++ b/lib/ddl/tests/ddl_test.php
@@ -31,9 +31,6 @@ class ddl_testcase extends database_driver_testcase {
     private $records= array();
 
     protected function setUp() {
-        //global $CFG;
-        //require_once($CFG->libdir . '/adminlib.php');
-
         parent::setUp();
 
         $table = new xmldb_table('test_table0');
@@ -131,6 +128,8 @@ class ddl_testcase extends database_driver_testcase {
      * Fill the given test table with some records, as far as
      * DDL behaviour must be tested both with real data and
      * with empty tables
+     * @param string $tablename
+     * @return int count of records
      */
     private function fill_deftable($tablename) {
         $DB = $this->tdb; // do not use global $DB!
diff --git a/lib/phpunit/lib.php b/lib/phpunit/lib.php
index 640e868eba1..58e80f01e35 100644
--- a/lib/phpunit/lib.php
+++ b/lib/phpunit/lib.php
@@ -945,10 +945,10 @@ class basic_testcase extends PHPUnit_Framework_TestCase {
  */
 class advanced_testcase extends PHPUnit_Framework_TestCase {
     /** @var bool automatically reset everything? null means log changes */
-    protected $resetAfterTest;
+    private $resetAfterTest;
 
     /** @var moodle_transaction */
-    protected $testdbtransaction;
+    private $testdbtransaction;
 
     /**
      * Constructs a test case with the given name.
@@ -1133,7 +1133,7 @@ class advanced_testcase extends PHPUnit_Framework_TestCase {
  */
 class database_driver_testcase extends PHPUnit_Framework_TestCase {
     /** @var moodle_database connection to extra database */
-    protected static $extradb = null;
+    private static $extradb = null;
 
     /** @var moodle_database used in these tests*/
     protected $tdb;
diff --git a/lib/tests/phpunit_test.php b/lib/tests/phpunit_test.php
index e651bbccc11..2910cbad412 100644
--- a/lib/tests/phpunit_test.php
+++ b/lib/tests/phpunit_test.php
@@ -192,7 +192,7 @@ class core_phpunit_advanced_testcase extends advanced_testcase {
         $this->assertSame($_SESSION['USER'], $USER);
     }
 
-    public function test_database_reset_repeated() {
+    public function test_database_reset() {
         global $DB;
 
         $this->resetAfterTest(true);
@@ -255,6 +255,66 @@ class core_phpunit_advanced_testcase extends advanced_testcase {
         $this->assertEquals(2, $DB->count_records('user'));
     }
 
+    public function test_change_detection() {
+        global $DB, $CFG, $COURSE, $SITE, $USER;
+
+        $this->preventResetByRollback();
+        phpunit_util::reset_all_data(true);
+
+        // database change
+        $this->assertEquals(1, $DB->get_field('user', 'confirmed', array('id'=>2)));
+        $DB->set_field('user', 'confirmed', 0, array('id'=>2));
+        try {
+            phpunit_util::reset_all_data(true);
+        } catch (Exception $e) {
+            $this->assertInstanceOf('PHPUnit_Framework_Error_Warning', $e);
+        }
+        $this->assertEquals(1, $DB->get_field('user', 'confirmed', array('id'=>2)));
+
+        // config change
+        $CFG->xx = 'yy';
+        unset($CFG->admin);
+        $CFG->rolesactive = 0;
+        try {
+            phpunit_util::reset_all_data(true);
+        } catch (Exception $e) {
+            $this->assertInstanceOf('PHPUnit_Framework_Error_Warning', $e);
+            $this->assertContains('xx', $e->getMessage());
+            $this->assertContains('admin', $e->getMessage());
+            $this->assertContains('rolesactive', $e->getMessage());
+        }
+        $this->assertFalse(isset($CFG->xx));
+        $this->assertTrue(isset($CFG->admin));
+        $this->assertEquals(1, $CFG->rolesactive);
+
+        //silent changes
+        $_SERVER['xx'] = 'yy';
+        phpunit_util::reset_all_data(true);
+        $this->assertFalse(isset($_SERVER['xx']));
+
+        // COURSE
+        $SITE->id = 10;
+        $COURSE = new stdClass();
+        $COURSE->id = 7;
+        try {
+            phpunit_util::reset_all_data(true);
+        } catch (Exception $e) {
+            $this->assertInstanceOf('PHPUnit_Framework_Error_Warning', $e);
+            $this->assertEquals(1, $SITE->id);
+            $this->assertSame($SITE, $COURSE);
+            $this->assertSame($SITE, $COURSE);
+        }
+
+        // USER change
+        $this->setUser(2);
+        try {
+            phpunit_util::reset_all_data(true);
+        } catch (Exception $e) {
+            $this->assertInstanceOf('PHPUnit_Framework_Error_Warning', $e);
+            $this->assertEquals(0, $USER->id);
+        }
+    }
+
     public function test_getDataGenerator() {
         $generator = $this->getDataGenerator();
         $this->assertInstanceOf('phpunit_data_generator', $generator);