Fix defaulted CatchAll constructor argument ordering

dataclass_wizard/_loaders.py

@@ -1247,6 +1247,11 @@ def load_func_for_dataclass(
         pre_assign = 'i+=1; '
         catch_all_field_stripped = catch_all_field.rstrip('?')
         catch_all_idx = cls_init_field_names.index(catch_all_field_stripped)
+        catch_all_field_def = cls_init_fields[catch_all_idx]
+        catch_all_has_default = (
+            catch_all_field_def.default is not MISSING
+            or catch_all_field_def.default_factory is not MISSING
+        )
         # remove catch all field from list, so we don't iterate over it
         del cls_init_fields[catch_all_idx]
     else:
@@ -1441,7 +1446,10 @@ def load_func_for_dataclass(
                 var = f'__{catch_all_field_stripped}'
                 fn_gen.add_line(f'{var} = {{}} if len(o) == i else {catch_all_def}')
 
-                if catch_all_field_stripped in cls_init_kw_only_field_names:
+                if (
+                    catch_all_has_default
+                    or catch_all_field_stripped in cls_init_kw_only_field_names
+                ):
                     kwargs.append(f'{catch_all_field_stripped}={var}')
                 else:
                     args.insert(catch_all_idx, var)

tests/unit/test_issue_251.py

@@ -0,0 +1,65 @@
+"""Regression coverage for CatchAll constructor argument ordering."""
+
+from dataclasses import dataclass, field, make_dataclass
+import sys
+from typing import Optional
+
+import pytest
+
+from dataclass_wizard import JSONWizard
+from dataclass_wizard.models import CatchAll
+
+
+@pytest.mark.parametrize('payload', [
+    {},
+    {'remember_me_cookie': 'abc'},
+    {'extra': 42},
+    {'remember_me_cookie': 'abc', 'extra': 42},
+])
+@pytest.mark.parametrize('kw_only', [False, True])
+def test_catch_all_after_defaulted_field(payload, kw_only):
+    """Defaulted fields must not receive the CatchAll positional value."""
+    if kw_only and sys.version_info < (3, 10):
+        pytest.skip('Keyword-only dataclass fields require Python 3.10')
+
+    @dataclass
+    class Foo(JSONWizard):
+        """Model with a defaulted field before its CatchAll field."""
+
+        remember_me_cookie: Optional[str] = None
+        extra_data: CatchAll = field(
+            default_factory=dict, **({'kw_only': True} if kw_only else {}))
+
+    result = Foo.from_dict(payload)
+
+    assert result.remember_me_cookie == payload.get('remember_me_cookie')
+    assert result.extra_data == {
+        key: value for key, value in payload.items()
+        if key != 'remember_me_cookie'
+    }
+
+
+@pytest.mark.parametrize('position', [0, 1, 2])
+def test_required_catch_all_field_position(position):
+    """Required CatchAll fields retain their positional argument order."""
+    fields = [('first', str), ('second', int)]
+    fields.insert(position, ('extras', CatchAll))
+    model = make_dataclass('Model', fields, bases=(JSONWizard,))
+    result = model.from_dict({'first': 'value', 'second': 7, 'extra': 42})
+    assert result.first == 'value'
+    assert result.second == 7
+    assert result.extras == {'extra': 42}
+
+
+def test_default_factory_catch_all_between_defaulted_fields():
+    """A default factory must work between other defaulted fields."""
+    @dataclass
+    class Model(JSONWizard):
+        """Model with a CatchAll field between two optional fields."""
+
+        first: str = 'default'
+        extras: CatchAll = field(default_factory=dict)
+        second: int = 0
+
+    result = Model.from_dict({'first': 'value', 'second': 7, 'extra': 42})
+    assert result == Model('value', {'extra': 42}, 7)