diff --git a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
index 6382341..322c7f4 100644
--- a/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Defines a base class for testing aggregator.module.
  */
-class AggregatorTestBase extends WebTestBase {
+abstract class AggregatorTestBase extends WebTestBase {
   function setUp() {
     parent::setUp(array('node', 'block', 'aggregator', 'aggregator_test'));
 
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentTestBase.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentTestBase.php
index 7f5f5cd..0975a8a 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentTestBase.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentTestBase.php
@@ -10,7 +10,7 @@ namespace Drupal\comment\Tests;
 use Drupal\comment\Comment;
 use Drupal\simpletest\WebTestBase;
 
-class CommentTestBase extends WebTestBase {
+abstract class CommentTestBase extends WebTestBase {
   protected $profile = 'standard';
 
   protected $admin_user;
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldAttachTestBase.php b/core/modules/field/lib/Drupal/field/Tests/FieldAttachTestBase.php
index 0e33a44..730b218 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldAttachTestBase.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldAttachTestBase.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\field\Tests;
 
-class FieldAttachTestBase extends FieldTestBase {
+abstract class FieldAttachTestBase extends FieldTestBase {
   function setUp() {
     // Since this is a base class for many test cases, support the same
     // flexibility that Drupal\simpletest\WebTestBase::setUp() has for the
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldTestBase.php b/core/modules/field/lib/Drupal/field/Tests/FieldTestBase.php
index 54d020f..c4a9d16 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldTestBase.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Parent class for Field API tests.
  */
-class FieldTestBase extends WebTestBase {
+abstract class FieldTestBase extends WebTestBase {
   var $default_storage = 'field_sql_storage';
 
   /**
diff --git a/core/modules/field_ui/lib/Drupal/field_ui/Tests/FieldUiTestBase.php b/core/modules/field_ui/lib/Drupal/field_ui/Tests/FieldUiTestBase.php
index 08ccd4a..d0dc547 100644
--- a/core/modules/field_ui/lib/Drupal/field_ui/Tests/FieldUiTestBase.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/Tests/FieldUiTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Provides common functionality for the Field UI test classes.
  */
-class FieldUiTestBase extends WebTestBase {
+abstract class FieldUiTestBase extends WebTestBase {
 
   function setUp() {
     // Since this is a base class for many test cases, support the same
diff --git a/core/modules/file/lib/Drupal/file/Tests/FileFieldTestBase.php b/core/modules/file/lib/Drupal/file/Tests/FileFieldTestBase.php
index d95cf86..726156f 100644
--- a/core/modules/file/lib/Drupal/file/Tests/FileFieldTestBase.php
+++ b/core/modules/file/lib/Drupal/file/Tests/FileFieldTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Provides methods specifically for testing File module's field handling.
  */
-class FileFieldTestBase extends WebTestBase {
+abstract class FileFieldTestBase extends WebTestBase {
   protected $profile = 'standard';
 
   protected $admin_user;
diff --git a/core/modules/image/lib/Drupal/image/Tests/ImageFieldTestBase.php b/core/modules/image/lib/Drupal/image/Tests/ImageFieldTestBase.php
index 51e85c6..86ab992 100644
--- a/core/modules/image/lib/Drupal/image/Tests/ImageFieldTestBase.php
+++ b/core/modules/image/lib/Drupal/image/Tests/ImageFieldTestBase.php
@@ -32,7 +32,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * This class provides methods specifically for testing Image's field handling.
  */
-class ImageFieldTestBase extends WebTestBase {
+abstract class ImageFieldTestBase extends WebTestBase {
   protected $admin_user;
 
   function setUp() {
diff --git a/core/modules/node/lib/Drupal/node/Tests/NodeTestBase.php b/core/modules/node/lib/Drupal/node/Tests/NodeTestBase.php
index 6e16adb..25eac61 100644
--- a/core/modules/node/lib/Drupal/node/Tests/NodeTestBase.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeTestBase.php
@@ -9,7 +9,7 @@ namespace Drupal\node\Tests;
 
 use Drupal\simpletest\WebTestBase;
 
-class NodeTestBase extends WebTestBase {
+abstract class NodeTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/path/lib/Drupal/path/Tests/PathTestBase.php b/core/modules/path/lib/Drupal/path/Tests/PathTestBase.php
index 120d5d2..4802572 100644
--- a/core/modules/path/lib/Drupal/path/Tests/PathTestBase.php
+++ b/core/modules/path/lib/Drupal/path/Tests/PathTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Provides a base class for testing the Path module.
  */
-class PathTestBase extends WebTestBase {
+abstract class PathTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/php/lib/Drupal/php/Tests/PhpTestBase.php b/core/modules/php/lib/Drupal/php/Tests/PhpTestBase.php
index 2af8c8b..675b146 100644
--- a/core/modules/php/lib/Drupal/php/Tests/PhpTestBase.php
+++ b/core/modules/php/lib/Drupal/php/Tests/PhpTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Defines a base PHP test case class.
  */
-class PhpTestBase extends WebTestBase {
+abstract class PhpTestBase extends WebTestBase {
   protected $php_code_format;
 
   function setUp() {
diff --git a/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php b/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
index a554dd9..c2ed0a4 100644
--- a/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
+++ b/core/modules/poll/lib/Drupal/poll/Tests/PollTestBase.php
@@ -9,7 +9,7 @@ namespace Drupal\poll\Tests;
 
 use Drupal\simpletest\WebTestBase;
 
-class PollTestBase extends WebTestBase {
+abstract class PollTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/search/lib/Drupal/search/Tests/SearchTestBase.php b/core/modules/search/lib/Drupal/search/Tests/SearchTestBase.php
index 0f1001b..35da57a 100644
--- a/core/modules/search/lib/Drupal/search/Tests/SearchTestBase.php
+++ b/core/modules/search/lib/Drupal/search/Tests/SearchTestBase.php
@@ -9,7 +9,7 @@ namespace Drupal\search\Tests;
 
 use Drupal\simpletest\WebTestBase;
 
-class SearchTestBase extends WebTestBase {
+abstract class SearchTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutTestBase.php b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutTestBase.php
index 830bbc1..4aca686 100644
--- a/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutTestBase.php
+++ b/core/modules/shortcut/lib/Drupal/shortcut/Tests/ShortcutTestBase.php
@@ -13,7 +13,7 @@ use stdClass;
 /**
  * Defines base class for shortcut test cases.
  */
-class ShortcutTestBase extends WebTestBase {
+abstract class ShortcutTestBase extends WebTestBase {
 
   /**
    * User with permission to administer shortcuts.
diff --git a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTestBase.php b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTestBase.php
index 1183155..c0d70ff 100644
--- a/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTestBase.php
+++ b/core/modules/statistics/lib/Drupal/statistics/Tests/StatisticsTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Defines a base class for testing the Statistics module.
  */
-class StatisticsTestBase extends WebTestBase {
+abstract class StatisticsTestBase extends WebTestBase {
 
   function setUp() {
     parent::setUp(array('node', 'block', 'statistics'));
diff --git a/core/modules/system/lib/Drupal/system/Tests/Ajax/AjaxTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Ajax/AjaxTestBase.php
index f3bfbe1..f517a23 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Ajax/AjaxTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Ajax/AjaxTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Base test system for AJAX tests.
  */
-class AjaxTestBase extends WebTestBase {
+abstract class AjaxTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/CacheTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Cache/CacheTestBase.php
index 75907e8..9046557 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Cache/CacheTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/CacheTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Provides helper methods for cache tests.
  */
-class CacheTestBase extends WebTestBase {
+abstract class CacheTestBase extends WebTestBase {
   protected $default_bin = 'page';
   protected $default_cid = 'test_temporary';
   protected $default_value = 'CacheTest';
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
index 0287fed..2fff06b 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/DatabaseTestBase.php
@@ -15,7 +15,7 @@ use Drupal\simpletest\WebTestBase;
  * Because all database tests share the same test data, we can centralize that
  * here.
  */
-class DatabaseTestBase extends WebTestBase {
+abstract class DatabaseTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/FileHookTestBase.php b/core/modules/system/lib/Drupal/system/Tests/File/FileHookTestBase.php
index 3c0673d..3f387fe 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/FileHookTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/FileHookTestBase.php
@@ -11,7 +11,7 @@ namespace Drupal\system\Tests\File;
  * Base class for file tests that use the file_test module to test uploads and
  * hooks.
  */
-class FileHookTestBase extends FileTestBase {
+abstract class FileHookTestBase extends FileTestBase {
   function setUp() {
     // Install file_test module
     parent::setUp('file_test');
diff --git a/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php b/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
index 2c72383..b2703eb 100644
--- a/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/File/FileTestBase.php
@@ -14,7 +14,7 @@ use stdClass;
  * Base class for file tests that adds some additional file specific
  * assertions and helper functions.
  */
-class FileTestBase extends WebTestBase {
+abstract class FileTestBase extends WebTestBase {
 
   function setUp() {
     $modules = func_get_args();
diff --git a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
index 53d723c..477475b 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Image/ToolkitTestBase.php
@@ -13,7 +13,7 @@ use stdClass;
 /**
  * Base class for image manipulation testing.
  */
-class ToolkitTestBase extends WebTestBase {
+abstract class ToolkitTestBase extends WebTestBase {
   protected $toolkit;
   protected $file;
   protected $image;
diff --git a/core/modules/system/lib/Drupal/system/Tests/Menu/MenuTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Menu/MenuTestBase.php
index ec8210c..217150e 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Menu/MenuTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Menu/MenuTestBase.php
@@ -9,7 +9,7 @@ namespace Drupal\system\Tests\Menu;
 
 use Drupal\simpletest\WebTestBase;
 
-class MenuTestBase extends WebTestBase {
+abstract class MenuTestBase extends WebTestBase {
   function setUp() {
     $modules = func_get_args();
     if (isset($modules[0]) && is_array($modules[0])) {
diff --git a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
index 1eeba4e..dff77e8 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Module/ModuleTestBase.php
@@ -15,7 +15,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Helper class for module test cases.
  */
-class ModuleTestBase extends WebTestBase {
+abstract class ModuleTestBase extends WebTestBase {
   protected $admin_user;
 
   function setUp() {
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TaxonomyTestBase.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TaxonomyTestBase.php
index b3b8760..37ec42b 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TaxonomyTestBase.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TaxonomyTestBase.php
@@ -12,7 +12,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Provides common helper methods for Taxonomy module tests.
  */
-class TaxonomyTestBase extends WebTestBase {
+abstract class TaxonomyTestBase extends WebTestBase {
 
   function setUp() {
     $modules = func_get_args();
diff --git a/core/modules/update/lib/Drupal/update/Tests/UpdateTestBase.php b/core/modules/update/lib/Drupal/update/Tests/UpdateTestBase.php
index fe603e2..19131bc 100644
--- a/core/modules/update/lib/Drupal/update/Tests/UpdateTestBase.php
+++ b/core/modules/update/lib/Drupal/update/Tests/UpdateTestBase.php
@@ -26,7 +26,7 @@ use Drupal\simpletest\WebTestBase;
 /**
  * Defines some shared functions used by all update tests.
  */
-class UpdateTestBase extends WebTestBase {
+abstract class UpdateTestBase extends WebTestBase {
 
   /**
    * Refreshes the update status based on the desired available update scenario.