Simplify argparser.type_check

If the value isn't param.default, it will always be a string or a flag, as
type_conv never gets called when the function is called from Python.

qutebrowser/commands/argparser.py

@@ -114,22 +114,17 @@ def type_conv(param, typ, value, *, str_choices=None):
     if value is param.default:
         return value
 
+    assert isinstance(value, str), repr(value)
+
     if utils.is_enum(typ):
-        if isinstance(value, typ):
-            return value
-        assert isinstance(value, str)
         _check_choices(param, value, [arg_name(e.name) for e in typ])
         return typ[value.replace('-', '_')]
     elif typ is str:
-        assert isinstance(value, str)
         if str_choices is not None:
             _check_choices(param, value, str_choices)
         return value
     elif callable(typ):
         # int, float, etc.
-        if isinstance(value, typ):
-            return value
-        assert isinstance(value, str)
         try:
             return typ(value)
         except (TypeError, ValueError):

qutebrowser/commands/command.py

@@ -415,6 +415,8 @@ class Command:
             value = argparser.type_conv(param, typ, value, str_choices=choices)
         elif typ is None:
             pass
+        elif typ is bool:  # no type conversion for flags
+            assert isinstance(value, bool)
         else:
             value = argparser.type_conv(param, typ, value)
 

tests/unit/commands/test_argparser.py

@@ -80,11 +80,9 @@ class TestArgumentParser:
 
 
 @pytest.mark.parametrize('types, value, expected', [
-    ([Enum], Enum.foo, Enum.foo),
     ([Enum], 'foo', Enum.foo),
     ([Enum], 'foo-bar', Enum.foo_bar),
 
-    ([int], 2, 2),
     ([int], '2', 2),
     ([int, str], 'foo', 'foo'),
 ])
@@ -132,12 +130,13 @@ def test_multitype_conv_invalid_type():
     assert str(excinfo.value) == "foo: Unknown type None!"
 
 
-def test_conv_default_param():
+@pytest.mark.parametrize('value, typ', [(None, None), (42, int)])
+def test_conv_default_param(value, typ):
     """The default value should always be a valid choice."""
-    def func(foo=None):
+    def func(foo=value):
         pass
     param = inspect.signature(func).parameters['foo']
-    assert argparser.type_conv(param, str, None, str_choices=['val']) is None
+    assert argparser.type_conv(param, typ, value, str_choices=['val']) == value
 
 
 def test_conv_str_type():