MDL-32149 add backup tests and dropping of extra tables

lib/tests/phpunit_test.php

@@ -37,7 +37,7 @@ defined('MOODLE_INTERNAL') || die();
 class core_phpunit_basic_testcase extends basic_testcase {
 
     /**
-     * Tests that bootstraping has occurred correctly
+     * Tests that bootstrapping has occurred correctly
      * @return void
      */
     public function test_bootstrap() {
@@ -99,4 +99,4 @@ class core_phpunit_advanced_testcase extends advanced_testcase {
         $this->assertEquals(0, $USER->id);
         $this->assertSame($_SESSION['USER'], $USER);
     }
-}
+}