* [misc] Enhance unit tests for instanceModel::randThirdDomain() method

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

module/instance/test/lib/instance.unittest.class.php

@@ -761,4 +761,20 @@ class instanceTest
 
         return $result;
     }
+
+    /**
+     * Test randThirdDomain method.
+     *
+     * @param  int $length
+     * @param  int $triedTimes
+     * @access public
+     * @return string
+     */
+    public function randThirdDomainTest(int $length = 4, int $triedTimes = 0): string
+    {
+        $result = $this->objectModel->randThirdDomain($length, $triedTimes);
+        if(dao::isError()) return dao::getError();
+
+        return $result;
+    }
 }