Add more unit test

Signed-off-by: Kebo Liu <[email protected]>

Author: keboliu

sonic-xcvrd/tests/test_xcvrd.py

@@ -583,6 +583,10 @@ def test_init_port_sfp_status_tbl(self):
     def test_load_media_settings_missing_file(self):
         assert media_settings_parser.load_media_settings() == {}
 
+    @patch('sonic_py_common.device_info.get_paths_to_platform_and_hwsku_dirs', MagicMock(return_value=('/invalid/path', '/invalid/path')))
+    def test_load_optical_si_settings_missing_file(self):
+        assert optics_si_parser.load_optics_si_settings() == {}
+
     @patch('xcvrd.xcvrd.platform_chassis')
     @patch('xcvrd.xcvrd.is_cmis_api')
     def test_get_media_settings_key(self, mock_is_cmis_api, mock_chassis):