core/modules/action/tests/src/Functional/ActionListTest.php         | 5 +++++
 core/modules/action/tests/src/Functional/ActionUninstallTest.php    | 5 +++++
 core/modules/action/tests/src/Functional/ConfigurationTest.php      | 6 ++++++
 .../action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php    | 5 +++++
 core/modules/aggregator/tests/src/Functional/AddFeedTest.php        | 5 +++++
 .../modules/aggregator/tests/src/Functional/AggregatorAdminTest.php | 5 +++++
 core/modules/comment/tests/src/Functional/CommentFieldsTest.php     | 5 +++++
 core/modules/filter/tests/src/Functional/FilterFormatAccessTest.php | 5 +++++
 core/modules/views/tests/src/Functional/UserBatchActionTest.php     | 5 +++++
 9 files changed, 46 insertions(+)

diff --git a/core/modules/action/tests/src/Functional/ActionListTest.php b/core/modules/action/tests/src/Functional/ActionListTest.php
index 6bb753e5e7..0c8ccb0932 100644
--- a/core/modules/action/tests/src/Functional/ActionListTest.php
+++ b/core/modules/action/tests/src/Functional/ActionListTest.php
@@ -18,6 +18,11 @@ class ActionListTest extends BrowserTestBase {
    */
   public static $modules = ['action'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * Tests the behavior when there are no actions to list in the admin page.
    */
diff --git a/core/modules/action/tests/src/Functional/ActionUninstallTest.php b/core/modules/action/tests/src/Functional/ActionUninstallTest.php
index 76170b1669..a256ddf90f 100644
--- a/core/modules/action/tests/src/Functional/ActionUninstallTest.php
+++ b/core/modules/action/tests/src/Functional/ActionUninstallTest.php
@@ -20,6 +20,11 @@ class ActionUninstallTest extends BrowserTestBase {
    */
   public static $modules = ['views', 'action'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * Tests Action uninstall.
    */
diff --git a/core/modules/action/tests/src/Functional/ConfigurationTest.php b/core/modules/action/tests/src/Functional/ConfigurationTest.php
index 9b9dcf62a0..a818be52dd 100644
--- a/core/modules/action/tests/src/Functional/ConfigurationTest.php
+++ b/core/modules/action/tests/src/Functional/ConfigurationTest.php
@@ -20,6 +20,12 @@ class ConfigurationTest extends BrowserTestBase {
    */
   public static $modules = ['action'];
 
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * Tests configuration of advanced actions through administration interface.
    */
diff --git a/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php b/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php
index f4c85fc755..66ebc40412 100644
--- a/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php
+++ b/core/modules/action/tests/src/FunctionalJavascript/ActionFormAjaxTest.php
@@ -18,6 +18,11 @@ class ActionFormAjaxTest extends WebDriverTestBase {
    */
   protected static $modules = ['action', 'action_form_ajax_test'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * {@inheritdoc}
    */
diff --git a/core/modules/aggregator/tests/src/Functional/AddFeedTest.php b/core/modules/aggregator/tests/src/Functional/AddFeedTest.php
index 88a1547b72..d01aa6bcd8 100644
--- a/core/modules/aggregator/tests/src/Functional/AddFeedTest.php
+++ b/core/modules/aggregator/tests/src/Functional/AddFeedTest.php
@@ -11,6 +11,11 @@
  */
 class AddFeedTest extends AggregatorTestBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   protected function setUp() {
     parent::setUp();
 
diff --git a/core/modules/aggregator/tests/src/Functional/AggregatorAdminTest.php b/core/modules/aggregator/tests/src/Functional/AggregatorAdminTest.php
index 53c1745a80..376783a523 100644
--- a/core/modules/aggregator/tests/src/Functional/AggregatorAdminTest.php
+++ b/core/modules/aggregator/tests/src/Functional/AggregatorAdminTest.php
@@ -11,6 +11,11 @@
  */
 class AggregatorAdminTest extends AggregatorTestBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * Tests the settings form to ensure the correct default values are used.
    */
diff --git a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
index 23ec524f33..1b6efb9251 100644
--- a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
@@ -22,6 +22,11 @@ class CommentFieldsTest extends CommentTestBase {
    */
   public static $modules = ['field_ui'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'classy';
+
   /**
    * Tests that the default 'comment_body' field is correctly added.
    */
diff --git a/core/modules/filter/tests/src/Functional/FilterFormatAccessTest.php b/core/modules/filter/tests/src/Functional/FilterFormatAccessTest.php
index f82d258ddf..abc9078a8e 100644
--- a/core/modules/filter/tests/src/Functional/FilterFormatAccessTest.php
+++ b/core/modules/filter/tests/src/Functional/FilterFormatAccessTest.php
@@ -21,6 +21,11 @@ class FilterFormatAccessTest extends BrowserTestBase {
    */
   public static $modules = ['block', 'filter', 'node'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * A user with administrative permissions.
    *
diff --git a/core/modules/views/tests/src/Functional/UserBatchActionTest.php b/core/modules/views/tests/src/Functional/UserBatchActionTest.php
index 60c1d25587..389d49846f 100644
--- a/core/modules/views/tests/src/Functional/UserBatchActionTest.php
+++ b/core/modules/views/tests/src/Functional/UserBatchActionTest.php
@@ -19,6 +19,11 @@ class UserBatchActionTest extends BrowserTestBase {
    */
   public static $modules = ['user', 'user_batch_action_test', 'views'];
 
+  /**
+   * {@inheritdoc}
+   */
+  protected $theme = 'stark';
+
   /**
    * Tests user admin batch.
    */