Allow providing a subset of args with --json-args

See #6091

2 files changed, 17 insertions, 1 deletions

diff --git a/qutebrowser/qutebrowser.py b/qutebrowser/qutebrowser.py
index fe8d824ec..135fdbe1b 100644
--- a/qutebrowser/qutebrowser.py
+++ b/qutebrowser/qutebrowser.py
@@ -190,8 +190,10 @@ def _unpack_json_args(args):
     construct a "fake" argparse.Namespace here based on the data loaded
     from json.
     """
+    new_args = vars(args)
     data = json.loads(args.json_args)
-    return argparse.Namespace(**data)
+    new_args.update(data)
+    return argparse.Namespace(**new_args)
 
 
 def main():
diff --git a/tests/unit/test_qutebrowser.py b/tests/unit/test_qutebrowser.py
index c553606c4..842e856ee 100644
--- a/tests/unit/test_qutebrowser.py
+++ b/tests/unit/test_qutebrowser.py
@@ -60,3 +60,17 @@ class TestLogFilter:
         _out, err = capsys.readouterr()
         print(err)
         assert 'Invalid log category invalid - valid categories' in err
+
+
+class TestJsonArgs:
+
+    def test_partial(self, parser):
+        """Make sure we can provide a subset of all arguments.
+
+        This ensures that it's possible to restart into an older version of qutebrowser
+        when a new argument was added.
+        """
+        args = parser.parse_args(['--json-args', '{"debug": true}'])
+        args = qutebrowser._unpack_json_args(args)
+        assert args.debug
+        assert not args.temp_basedir