diff --git a/core/modules/system/tests/modules/menu_test/src/Controller/MenuTestController.php b/core/modules/system/tests/modules/menu_test/src/Controller/MenuTestController.php
index c5088e8..8a38b2a 100644
--- a/core/modules/system/tests/modules/menu_test/src/Controller/MenuTestController.php
+++ b/core/modules/system/tests/modules/menu_test/src/Controller/MenuTestController.php
@@ -73,7 +73,7 @@ public static function create(ContainerInterface $container) {
    *   A string that can be used for comparison.
    */
   public function menuTestCallback() {
-    return ['#markup' => 'This is the menuTestCallback content.'];
+    return ['#markup' => 'This is the menuTestCallback content.', '#cache' => []];
   }
 
 
@@ -114,7 +114,7 @@ public function themePage($inherited) {
     if ($inherited) {
       $output .= ' Theme negotiation inheritance is being tested.';
     }
-    return ['#markup' => $output];
+    return ['#markup' => $output, '#cache' => []];
   }
 
   /**
diff --git a/core/modules/system/tests/modules/menu_test/src/TestControllers.php b/core/modules/system/tests/modules/menu_test/src/TestControllers.php
index a7e39e4..c14f2d4 100644
--- a/core/modules/system/tests/modules/menu_test/src/TestControllers.php
+++ b/core/modules/system/tests/modules/menu_test/src/TestControllers.php
@@ -18,21 +18,21 @@ class TestControllers {
    * Returns page to be used as a login path.
    */
   public function testLogin() {
-    return ['#markup' => 'This is TestControllers::testLogin.'];
+    return ['#markup' => 'This is TestControllers::testLogin.', '#cache' => []];
   }
 
   /**
    * Prints out test data.
    */
   public function test1() {
-    return ['#markup' => 'test1'];
+    return ['#markup' => 'test1', '#cache' => []];
   }
 
   /**
    * Prints out test data.
    */
   public function test2() {
-    return ['#markup' => 'test2'];
+    return ['#markup' => 'test2', '#cache' => []];
   }
 
   /**
@@ -43,14 +43,14 @@ public function testSession() {
       $_SESSION['menu_test'] = 0;
     }
     $_SESSION['menu_test']++;
-    return ['#markup' => SafeMarkup::format('Session menu_test is @count', ['@count' => $_SESSION['menu_test']])];
+    return ['#markup' => SafeMarkup::format('Session menu_test is @count', ['@count' => $_SESSION['menu_test']]), '#cache' => []];
   }
 
   /**
    * Prints out test data.
    */
   public function testDerived() {
-    return ['#markup' => 'testDerived'];
+    return ['#markup' => 'testDerived', '#cache' => []];
   }
 
   /**
@@ -64,10 +64,10 @@ public function testDerived() {
    */
   public function testDefaults($placeholder = NULL) {
     if ($placeholder) {
-      return ['#markup' => SafeMarkup::format("Sometimes there is a placeholder: '@placeholder'.", array('@placeholder' => $placeholder))];
+      return ['#markup' => SafeMarkup::format("Sometimes there is a placeholder: '@placeholder'.", array('@placeholder' => $placeholder)), '#cache' => []];
     }
     else {
-      return ['#markup' => 'Sometimes there is no placeholder.'];
+      return ['#markup' => 'Sometimes there is no placeholder.', '#cache' => []];
     }
   }
 
@@ -77,6 +77,7 @@ public function testDefaults($placeholder = NULL) {
   public function testContextual() {
     return [
       '#markup' => 'testContextual',
+      '#cache' => [],
       'stuff' => [
         '#type' => 'contextual_links',
         '#contextual_links' => [
diff --git a/core/modules/system/tests/modules/paramconverter_test/src/TestControllers.php b/core/modules/system/tests/modules/paramconverter_test/src/TestControllers.php
index 327a8d5..76a20e3 100644
--- a/core/modules/system/tests/modules/paramconverter_test/src/TestControllers.php
+++ b/core/modules/system/tests/modules/paramconverter_test/src/TestControllers.php
@@ -17,15 +17,15 @@ class TestControllers {
 
   public function testUserNodeFoo(EntityInterface $user, NodeInterface $node, $foo) {
     $foo = is_object($foo) ? $foo->label() : $foo;
-    return ['#markup' => "user: {$user->label()}, node: {$node->label()}, foo: $foo"];
+    return ['#markup' => "user: {$user->label()}, node: {$node->label()}, foo: $foo", '#cache' => []];
   }
 
   public function testNodeSetParent(NodeInterface $node, NodeInterface $parent) {
-    return ['#markup' => "Setting '{$parent->label()}' as parent of '{$node->label()}'."];
+    return ['#markup' => "Setting '{$parent->label()}' as parent of '{$node->label()}'.", '#cache' => []];
   }
 
   public function testEntityLanguage(NodeInterface $node) {
-    $build = ['#markup' => $node->label()];
+    $build = ['#markup' => $node->label(), '#cache' => []];
     \Drupal::service('renderer')->addCacheableDependency($build, $node);
     return $build;
   }
diff --git a/core/modules/system/tests/modules/router_test_directory/src/TestControllers.php b/core/modules/system/tests/modules/router_test_directory/src/TestControllers.php
index 40fad0b..6d06ed4 100644
--- a/core/modules/system/tests/modules/router_test_directory/src/TestControllers.php
+++ b/core/modules/system/tests/modules/router_test_directory/src/TestControllers.php
@@ -29,19 +29,19 @@ public function test1() {
   }
 
   public function test2() {
-    return ['#markup' => "test2"];
+    return ['#markup' => "test2", '#cache' => []];
   }
 
   public function test3($value) {
-    return ['#markup' => $value];
+    return ['#markup' => $value, '#cache' => []];
   }
 
   public function test4($value) {
-    return ['#markup' => $value];
+    return ['#markup' => $value, '#cache' => []];
   }
 
   public function test5() {
-    return ['#markup' => "test5"];
+    return ['#markup' => "test5", '#cache' => []];
   }
 
   public function test6() {
diff --git a/core/modules/system/tests/modules/session_test/src/Controller/SessionTestController.php b/core/modules/system/tests/modules/session_test/src/Controller/SessionTestController.php
index 3af2ea5..dc8aa54 100644
--- a/core/modules/system/tests/modules/session_test/src/Controller/SessionTestController.php
+++ b/core/modules/system/tests/modules/session_test/src/Controller/SessionTestController.php
@@ -26,7 +26,7 @@ class SessionTestController extends ControllerBase {
   public function get() {
     return empty($_SESSION['session_test_value'])
       ? []
-      : ['#markup' => $this->t('The current value of the stored session variable is: %val', array('%val' => $_SESSION['session_test_value']))];
+      : ['#markup' => $this->t('The current value of the stored session variable is: %val', array('%val' => $_SESSION['session_test_value'])), '#cache' => []];
   }
 
   /**
@@ -42,7 +42,7 @@ public function getFromSessionObject(Request $request) {
     $value = $request->getSession()->get("session_test_key");
     return empty($value)
       ? []
-      : ['#markup' => $this->t('The current value of the stored session variable is: %val', array('%val' => $value))];
+      : ['#markup' => $this->t('The current value of the stored session variable is: %val', array('%val' => $value)), '#cache' => []];
   }
 
   /**
@@ -61,7 +61,7 @@ public function getId(Request $request) {
 
     $request->getSession()->save();
 
-    return ['#markup' => 'session_id:' . session_id() . "\n"];
+    return ['#markup' => 'session_id:' . session_id() . "\n", '#cache' => []];
   }
 
   /**
@@ -89,7 +89,7 @@ public function getIdFromCookie(Request $request) {
   public function set($test_value) {
     $_SESSION['session_test_value'] = $test_value;
 
-    return ['#markup' => $this->t('The current value of the stored session variable has been set to %val', array('%val' => $test_value))];
+    return ['#markup' => $this->t('The current value of the stored session variable has been set to %val', array('%val' => $test_value)), '#cache' => []];
   }
 
   /**
@@ -105,7 +105,7 @@ public function set($test_value) {
   public function noSet($test_value) {
     \Drupal::service('session_handler.write_safe')->setSessionWritable(FALSE);
     $this->set($test_value);
-    return ['#markup' => $this->t('session saving was disabled, and then %val was set', array('%val' => $test_value))];
+    return ['#markup' => $this->t('session saving was disabled, and then %val was set', array('%val' => $test_value)), '#cache' => []];
   }
 
   /**
@@ -131,7 +131,7 @@ public function setMessage() {
   public function setMessageButDontSave() {
     \Drupal::service('session_handler.write_safe')->setSessionWritable(FALSE);
     $this->setMessage();
-    return ['#markup' => ''];
+    return ['#markup' => '', '#cache' => []];
   }
 
   /**
@@ -141,7 +141,7 @@ public function setMessageButDontSave() {
    *   A notification message.
    */
   public function isLoggedIn() {
-    return ['#markup' => $this->t('User is logged in.')];
+    return ['#markup' => $this->t('User is logged in.'), '#cache' => []];
   }
 
   /**