[CI] Add five unittest (#4958)

* add unittest

* Update test_logger.py

tests/logger/test_logger.py

@@ -30,7 +30,7 @@ class LoggerTests(unittest.TestCase):
         self.env_patchers = [
             patch("fastdeploy.envs.FD_LOG_DIR", self.tmp_dir),
             patch("fastdeploy.envs.FD_DEBUG", 0),
-            patch("fastdeploy.envs.FD_LOG_BACKUP_COUNT", "1"),
+            patch("fastdeploy.envs.FD_LOG_BACKUP_COUNT", 1),
         ]
         for p in self.env_patchers:
             p.start()
@@ -77,5 +77,54 @@ class LoggerTests(unittest.TestCase):
         self.assertTrue(legacy_logger.propagate)
 
 
+class LoggerExtraTests(unittest.TestCase):
+    def setUp(self):
+        self.logger = FastDeployLogger()
+
+    def tearDown(self):
+        if hasattr(FastDeployLogger, "_instance"):
+            FastDeployLogger._instance = None
+        if hasattr(FastDeployLogger, "_initialized"):
+            FastDeployLogger._initialized = False
+
+    def test_singleton_behavior(self):
+        """Ensure multiple instances are same"""
+        a = FastDeployLogger()
+        b = FastDeployLogger()
+        self.assertIs(a, b)
+
+    def test_initialize_only_once(self):
+        """Ensure _initialize won't re-run if already initialized"""
+        self.logger._initialized = True
+        with patch("fastdeploy.logger.logger.setup_logging") as mock_setup:
+            self.logger._initialize()
+            mock_setup.assert_not_called()
+
+    def test_get_logger_unified_path(self):
+        """Directly test get_logger unified path"""
+        with patch("fastdeploy.logger.logger.setup_logging") as mock_setup:
+            log = self.logger.get_logger("utils")
+            self.assertTrue(log.name.startswith("fastdeploy."))
+            mock_setup.assert_called_once()
+
+    def test_get_logger_legacy_path(self):
+        """Test legacy get_logger path"""
+        with patch("fastdeploy.logger.logger.FastDeployLogger._get_legacy_logger") as mock_legacy:
+            self.logger.get_logger("x", "y.log", False, False)
+            mock_legacy.assert_called_once()
+
+    def test_get_legacy_logger_debug_mode(self):
+        """Ensure debug level is set when FD_DEBUG=1"""
+        with patch("fastdeploy.envs.FD_DEBUG", 1):
+            logger = self.logger._get_legacy_logger("debug_case", "d.log")
+            self.assertEqual(logger.level, logging.DEBUG)
+
+    def test_get_legacy_logger_without_formatter(self):
+        """Test legacy logger without formatter"""
+        logger = self.logger._get_legacy_logger("nofmt", "n.log", without_formater=True)
+        for h in logger.handlers:
+            self.assertIsNone(h.formatter)
+
+
 if __name__ == "__main__":
     unittest.main(verbosity=2)