Issue #3275357: AU Extensions module became unhidden

automatic_updates_extensions/tests/src/Unit/EnsureHiddenTest.php

+<?php
+
+namespace Drupal\Tests\automatic_updates_extensions\Unit;
+
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\Yaml\Yaml;
+
+/**
+ * Test to ensure the module is hidden.
+ *
+ * @group automatic_updates_extensions
+ */
+class EnsureHiddenTest extends UnitTestCase {
+
+  /**
+   * Tests that module is hidden.
+   */
+  public function testModuleIsHidden() {
+    $info = Yaml::parseFile(__DIR__ . '/../../../automatic_updates_extensions.info.yml');
+    $this->assertSame(TRUE, $info['hidden']);
+  }
+
+}