Follow-up #2987939: Fixed @covers errors while running DirectoryTest.

tests/src/Kernel/DirectoryTest.php

@@ -12,8 +12,12 @@ class DirectoryTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
-    parent::setUp();
+  public static function setUpBeforeClass() {
+    parent::setUpBeforeClass();
+
+    // This is required to not fail the @covers for global functions.
+    // @todo Once xmlsitemap_clear_directory() is refactored to auto-loadable code, remove this require statement.
+    require_once __DIR__ . '/../../../xmlsitemap.module';
   }
 
   /**