add pytest for modify_args

tests/test_utils/test_modify_args.py

@@ -0,0 +1,19 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import argparse
+from unittest.mock import patch
+
+from mmedit.utils import modify_args
+
+
+def test_modify_args():
+
+    def _parse_args():
+        parser = argparse.ArgumentParser(description='Generation demo')
+        parser.add_argument('--config-path', help='test config file path')
+        args = parser.parse_args()
+        return args
+
+    with patch('argparse._sys.argv', ['test.py', '--config_path=config.py']):
+        modify_args()
+        args = _parse_args()
+        assert args.config_path == 'config.py'