diff --git a/core/modules/contact/tests/src/Unit/MailHandlerTest.php b/core/modules/contact/tests/src/Unit/MailHandlerTest.php
index 439e5077bf..78ace85b91 100644
--- a/core/modules/contact/tests/src/Unit/MailHandlerTest.php
+++ b/core/modules/contact/tests/src/Unit/MailHandlerTest.php
@@ -9,6 +9,7 @@
 use Drupal\Core\Language\Language;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Tests\UnitTestCase;
+use Drupal\user\Entity\User;
 
 /**
  * @coversDefaultClass \Drupal\contact\MailHandler
@@ -292,7 +293,7 @@ public function getSendMailMessages() {
    *   Mock sender for testing.
    */
   protected function getMockSender($anonymous = TRUE, $mail_address = 'anonymous@drupal.org') {
-    $sender = $this->createMock('\Drupal\Core\Session\AccountInterface');
+    $sender = $this->createMock(User::class);
     $sender->expects($this->once())
       ->method('isAnonymous')
       ->willReturn($anonymous);
diff --git a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
index 0560901888..c20cfe45a4 100644
--- a/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
+++ b/core/tests/Drupal/Tests/Component/DependencyInjection/ContainerTest.php
@@ -168,7 +168,7 @@ public function testGet() {
     $this->assertEquals($some_parameter, $service->getSomeParameter(), '%some_config% was injected via constructor.');
     $this->assertEquals($this->container, $service->getContainer(), 'Container was injected via setter injection.');
     $this->assertEquals($some_other_parameter, $service->getSomeOtherParameter(), '%some_other_config% was injected via setter injection.');
-    $this->assertEquals('foo', $service->_someProperty, 'Service has added properties.');
+    $this->assertEquals('foo', $service->someProperty, 'Service has added properties.');
   }
 
   /**
@@ -741,7 +741,7 @@ protected function getMockContainerDefinition() {
         $this->getServiceCall('other.service'),
         $this->getParameterCall('some_config'),
       ]),
-      'properties' => $this->getCollection(['_someProperty' => 'foo']),
+      'properties' => $this->getCollection(['someProperty' => 'foo']),
       'calls' => [
         [
           'setContainer',
@@ -1106,6 +1106,11 @@ class MockService {
    */
   protected $someOtherParameter;
 
+  /**
+   * @var string
+   */
+  public $someProperty;
+
   /**
    * Constructs a MockService object.
    *
diff --git a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
index 9c160facbc..f2de6017ad 100644
--- a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
@@ -514,6 +514,7 @@ public function testSort() {
       ->will($this->returnValue([
         'entity_keys' => [
           'label' => 'label',
+          'weight' => 'weight',
         ],
       ]));
 
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityLinkTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityLinkTest.php
index 20624988f8..8994e06f6c 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityLinkTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityLinkTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\Core\Entity;
 
+use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Language\Language;
@@ -93,7 +94,7 @@ public function testToLink($entity_label, $link_text, $expected_text, $link_rel
       ->will($this->returnValue($entity_type));
 
     /** @var \Drupal\Core\Entity\Entity $entity */
-    $entity = $this->getMockForAbstractClass('Drupal\Core\Entity\EntityBase', [
+    $entity = $this->getMockForAbstractClass(ConfigEntityBase::class, [
       ['id' => $entity_id, 'label' => $entity_label, 'langcode' => 'es'],
       $entity_type_id,
     ]);