only in patch2:
unchanged:
--- a/tests/src/Unit/MailsystemManagerTest.php
+++ b/tests/src/Unit/MailsystemManagerTest.php
@@ -68,10 +68,9 @@ class MailsystemManagerTest extends UnitTestCase {
 
     $theme_manager = $this->prophesize(ThemeManager::class);
     $theme_initialization = $this->prophesize(ThemeInitialization::class);
-    $default_theme_registry = $this->prophesize(Registry::class);
-    $mail_theme_registry = $this->prophesize(Registry::class);
+    $renderer = $this->getMock('\Drupal\Core\Render\RendererInterface');
 
-    $this->mailManager = new MailsystemManager($namespaces, $cache_backend, $module_handler, $this->configFactory, $logger_factory, $string_translation, $theme_manager->reveal(), $theme_initialization->reveal(), $default_theme_registry->reveal(), $mail_theme_registry->reveal());
+    $this->mailManager = new MailsystemManager($namespaces, $cache_backend, $module_handler, $this->configFactory, $logger_factory, $string_translation, $theme_manager->reveal(), $theme_initialization->reveal(), $renderer);
   }
 
   public function testGetInstances_Default() {