Add test case for loading port configuration

tests/sfputil_test.py

@@ -1412,3 +1412,11 @@ def test_target_firmware(self, mock_chassis):
         result = runner.invoke(sfputil.cli.commands['firmware'].commands['target'], ["Ethernet0", "1"])
         assert result.output == 'Target Mode set failed!\n'
         assert result.exit_code == EXIT_FAIL
+
+    @patch('sfputil.main.multi_asic.is_multi_asic', MagicMock(return_value=True))
+    @patch('sfputil.main.platform_sfputil', MagicMock())
+    @patch('sfputil.main.device_info.get_paths_to_platform_and_hwsku_dirs',
+        MagicMock(return_value=(None, None)))
+    @patch('sfputil.main.device_info.get_path_to_port_config_file', MagicMock(return_value=('')))
+    def test_load_port_config(self):
+        assert sfputil.load_port_config() == True