diff -u b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/ExtensionTest.php b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/ExtensionTest.php
--- b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/ExtensionTest.php
+++ b/core/modules/system/tests/src/Kernel/Plugin/migrate/source/ExtensionTest.php
@@ -10,7 +10,7 @@
  * @covers \Drupal\system\Plugin\migrate\source\Extension
  * @group migrate_drupal
  */
-class SourceLegacyExtensionTest extends MigrateSqlSourceTestBase {
+class ExtensionTest extends MigrateSqlSourceTestBase {
 
   /**
    * {@inheritdoc}