only in patch2:
unchanged:
--- a/tests/src/Unit/panels_ipe/RequestHandlerTestBase.php
+++ b/tests/src/Unit/panels_ipe/RequestHandlerTestBase.php
@@ -6,6 +6,7 @@ namespace Drupal\Tests\panels\Unit\panels_ipe;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\panels\Plugin\DisplayVariant\PanelsDisplayVariant;
 use Drupal\panels\Storage\PanelsStorageManagerInterface;
+use Drupal\Tests\RandomGeneratorTrait;
 use Drupal\user\SharedTempStore;
 use PHPUnit_Framework_MockObject_MockObject;
 use Symfony\Component\HttpFoundation\JsonResponse;
@@ -16,6 +17,8 @@ use Symfony\Component\HttpFoundation\Request;
  */
 abstract class RequestHandlerTestBase extends \PHPUnit_Framework_TestCase {
 
+  use RandomGeneratorTrait;
+
   /** @var  \Drupal\panels_ipe\Helpers\RequestHandlerInterface */
   protected $sut;
 
@@ -35,13 +38,17 @@ abstract class RequestHandlerTestBase extends \PHPUnit_Framework_TestCase {
     parent::setUp();
     $this->moduleHandler = $this->getMockForAbstractClass(ModuleHandlerInterface::class);
     $this->panelsStore = $this->getMockForAbstractClass(PanelsStorageManagerInterface::class);
-    $this->tempStore = $this->getMockBuilder(SharedTempstore::class)
+    $this->tempStore = $this->getMockBuilder(SharedTempStore::class)
       ->disableOriginalConstructor()
       ->getMock();
 
     $this->panelsDisplay = $this->getMockBuilder(PanelsDisplayVariant::class)
       ->disableOriginalConstructor()
       ->getMock();
+
+    $this->panelsDisplay->method('id')->willReturn(
+      $this->randomMachineName(16)
+    );
   }
 
   protected function createRequest($content = NULL) {