diff --git a/core/modules/system/src/Tests/Batch/PageTest.php b/core/modules/system/src/Tests/Batch/PageTest.php
index 42800b7..c4b1b70 100644
--- a/core/modules/system/src/Tests/Batch/PageTest.php
+++ b/core/modules/system/src/Tests/Batch/PageTest.php
@@ -17,6 +17,15 @@
 class PageTest extends WebTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/Entity/EntityViewControllerTest.php b/core/modules/system/src/Tests/Entity/EntityViewControllerTest.php
index aa2d800..93f75df 100644
--- a/core/modules/system/src/Tests/Entity/EntityViewControllerTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityViewControllerTest.php
@@ -17,6 +17,15 @@
 class EntityViewControllerTest extends WebTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php b/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
index 50d299c..36c17d9 100644
--- a/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
+++ b/core/modules/system/src/Tests/Extension/ThemeHandlerTest.php
@@ -19,6 +19,15 @@
 class ThemeHandlerTest extends KernelTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/Form/FormObjectTest.php b/core/modules/system/src/Tests/Form/FormObjectTest.php
index 237d9e7..c41928a 100644
--- a/core/modules/system/src/Tests/Form/FormObjectTest.php
+++ b/core/modules/system/src/Tests/Form/FormObjectTest.php
@@ -18,6 +18,15 @@
 class FormObjectTest extends SystemConfigFormTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/Menu/BreadcrumbTest.php b/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
index ee54f31..3a08cf3 100644
--- a/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
+++ b/core/modules/system/src/Tests/Menu/BreadcrumbTest.php
@@ -19,6 +19,15 @@
 class BreadcrumbTest extends MenuTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/Menu/MenuRouterTest.php b/core/modules/system/src/Tests/Menu/MenuRouterTest.php
index 7de9006..4dd2e19 100644
--- a/core/modules/system/src/Tests/Menu/MenuRouterTest.php
+++ b/core/modules/system/src/Tests/Menu/MenuRouterTest.php
@@ -17,6 +17,15 @@
 class MenuRouterTest extends WebTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/System/PageTitleTest.php b/core/modules/system/src/Tests/System/PageTitleTest.php
index 98148cd..31020c9 100644
--- a/core/modules/system/src/Tests/System/PageTitleTest.php
+++ b/core/modules/system/src/Tests/System/PageTitleTest.php
@@ -20,6 +20,15 @@
 class PageTitleTest extends WebTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array
diff --git a/core/modules/system/src/Tests/System/ThemeTest.php b/core/modules/system/src/Tests/System/ThemeTest.php
index 80d469a..8a7fd04 100644
--- a/core/modules/system/src/Tests/System/ThemeTest.php
+++ b/core/modules/system/src/Tests/System/ThemeTest.php
@@ -19,6 +19,15 @@
 class ThemeTest extends WebTestBase {
 
   /**
+   * Set to TRUE to strict check all configuration saved.
+   *
+   * @see \Drupal\Core\Config\Testing\ConfigSchemaChecker
+   *
+   * @var bool
+   */
+  protected $strictConfigSchema = TRUE;
+
+  /**
    * Modules to enable.
    *
    * @var array