diff -u b/core/modules/system/src/Tests/Module/InstallUninstallTest.php b/core/modules/system/src/Tests/Module/InstallUninstallTest.php
--- b/core/modules/system/src/Tests/Module/InstallUninstallTest.php
+++ b/core/modules/system/src/Tests/Module/InstallUninstallTest.php
@@ -88,7 +88,7 @@
       // List the module display names to check the confirmation message.
       $module_names = array();
       foreach ($modules_to_install as $module_to_install) {
-        $module_names[] = $module->info['name'];
+        $module_names[] = $all_modules[$module_to_install]->info['name'];
       }
       $expected_text = \Drupal::translation()->formatPlural(count($module_names), 'Module @name has been enabled.', '@count modules have been enabled: @names.', array(
         '@name' => $module_names[0],