Narrow down implicit boolean conversion introduced in 0.5.8

dataclasses_json/core.py

@@ -244,7 +244,16 @@ def _support_extended_types(field_type, field_value):
         res = (field_value
                if isinstance(field_value, UUID)
                else UUID(field_value))
-    elif _issubclass_safe(field_type, (int, float, str, bool)):
+    elif _issubclass_safe(field_type, bool):
+        # issubclass(bool, int) -> True
+        # thus values >1 will always convert to True in the next clause, unless intercepted
+        if field_value in ('True', 'true', True, 1):
+            res = True
+        elif field_value in ('False', 'false', False, 0):
+            res = False
+        else:
+            raise ValueError(f"Value {field_value} of input type {field_type.__name__} cannot be decoded as boolean")
+    elif _issubclass_safe(field_type, int) or _issubclass_safe(field_type, float) or _issubclass_safe(field_type, str):
         res = (field_value
                if isinstance(field_value, field_type)
                else field_type(field_value))

dataclasses_json/utils.py

@@ -111,7 +111,7 @@ def _isinstance_safe(o, t):
         return result
 
 
-def _issubclass_safe(cls, classinfo):
+def _issubclass_safe(cls: Type[Any], classinfo: Type[Any]) -> bool:
     try:
         return issubclass(cls, classinfo)
     except Exception:

tests/test_builtins.py

@@ -1,7 +1,8 @@
 from dataclasses import dataclass
 from decimal import Decimal
-from typing import Optional
+from typing import Optional, Dict
 
+import pytest
 from pytest import mark, param
 
 
@@ -13,22 +14,53 @@ class DataClassWithBuiltins(DataClassJsonMixin):
     actually_a_str: str
     actually_an_int: int
     actually_a_float: float
+    actually_a_bool: bool
 
 
 @mark.parametrize(
     "model_dict, expected_model",
     [
         param(
-            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1},
-            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1),
+            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1, "actually_a_bool": True},
+            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1, actually_a_bool=True),
             id="Happy case"
         ),
         param(
-            {"actually_a_str": "str", "actually_an_int": Decimal("42.1"), "actually_a_float": Decimal("42.1")},
-            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1),
+            {"actually_a_str": "str", "actually_an_int": Decimal("42.1"), "actually_a_float": Decimal("42.1"), "actually_a_bool": True },
+            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1, actually_a_bool=True),
             id="Decimal as int and float"
         ),
+        param(
+            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1, "actually_a_bool": "False"},
+            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1,
+                                  actually_a_bool=False),
+            id="Bool passed as a valid string"
+        ),
+        param(
+            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1, "actually_a_bool": 1},
+            DataClassWithBuiltins(actually_a_str="str", actually_an_int=42, actually_a_float=42.1,
+                                  actually_a_bool=True),
+            id="Bool passed using valid discrete integer range [0,1]"
+        ),
     ]
 )
-def test__DataClassWithBuiltins__from_dict(model_dict, expected_model):
+def test_dataclass_with_implicit_builtins(model_dict: Dict, expected_model: DataClassWithBuiltins):
     assert DataClassWithBuiltins.from_dict(model_dict) == expected_model
+
+
+@mark.parametrize(
+    "model_dict",
+    [
+        param(
+            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1, "actually_a_bool": 1234},
+            id="Bool passed using invalid integer"
+        ),
+        param(
+            {"actually_a_str": "str", "actually_an_int": 42, "actually_a_float": 42.1, "actually_a_bool": "0"},
+            id="Bool passed using a string rather than an integer or a boolean string"
+        ),
+    ]
+)
+def test_dataclass_with_implicit_builtins_failed_bool(model_dict: Dict):
+    with pytest.raises(ValueError):
+        DataClassWithBuiltins.from_dict(model_dict)