Fix type hints and enable mypy (#486)

Author: KapJI

.github/workflows/tests.yml

@@ -15,6 +15,7 @@ jobs:
       matrix:
         include:
           - { python-version: "3.10", session: "flake8" }
+          - { python-version: "3.10", session: "mypy" }
           - { python-version: "3.10", session: "py310" }
           - { python-version: "3.9",  session: "py39" }
           - { python-version: "3.8",  session: "py38" }

tox.ini

@@ -22,3 +22,9 @@ commands =
 [testenv:flake8]
 deps = flake8
 commands = flake8 --doctests setup.py voluptuous
+
+[testenv:mypy]
+deps =
+    mypy
+    pytest
+commands = mypy voluptuous

voluptuous/error.py

@@ -21,14 +21,22 @@ class Invalid(Error):
 
     def __init__(self, message: str, path: typing.Optional[typing.List[str]] = None, error_message: typing.Optional[str] = None, error_type: typing.Optional[str] = None) -> None:
         Error.__init__(self, message)
-        self.path = path or []
-        self.error_message = error_message or message
+        self._path = path or []
+        self._error_message = error_message or message
         self.error_type = error_type
 
     @property
     def msg(self) -> str:
         return self.args[0]
 
+    @property
+    def path(self) -> typing.List[str]:
+        return self._path
+
+    @property
+    def error_message(self) -> str:
+        return self._error_message
+
     def __str__(self) -> str:
         path = ' @ data[%s]' % ']['.join(map(repr, self.path)) \
             if self.path else ''
@@ -38,7 +46,7 @@ def __str__(self) -> str:
         return output + path
 
     def prepend(self, path: typing.List[str]) -> None:
-        self.path = path + self.path
+        self._path = path + self.path
 
 
 class MultipleInvalid(Invalid):

voluptuous/schema_builder.py

@@ -165,11 +165,11 @@ def Extra(_) -> None:
 primitive_types = (bool, bytes, int, long, str, unicode, float, complex)
 
 Schemable = typing.Union[
-    Extra, 'Schema', 'Object',
+    'Schema', 'Object',
     _Mapping,
     list, tuple, frozenset, set,
     bool, bytes, int, long, str, unicode, float, complex,
-    type, object, dict, type(None), typing.Callable
+    type, object, dict, None, typing.Callable
 ]
 
 
@@ -753,8 +753,7 @@ def extend(self, schema: Schemable, required: typing.Optional[bool] = None, extr
         :param extra: if set, overrides `extra` of this `Schema`
         """
 
-        assert type(self.schema) == dict and type(schema) == dict, 'Both schemas must be dictionary-based'
-        assert isinstance(self.schema, dict)
+        assert isinstance(self.schema, dict) and isinstance(schema, dict), 'Both schemas must be dictionary-based'
 
         result = self.schema.copy()
 
@@ -779,7 +778,7 @@ def key_literal(key):
 
                 # if both are dictionaries, we need to extend recursively
                 # create the new extended sub schema, then remove the old key and add the new one
-                if type(result_value) == dict and type(value) == dict:
+                if isinstance(result_value, dict) and isinstance(value, dict):
                     new_value = Schema(result_value).extend(value).schema
                     del result[result_key]
                     result[key] = new_value

voluptuous/tests/tests.py

@@ -167,7 +167,7 @@ def test_literal():
     except MultipleInvalid as e:
         assert str(e) == "{'b': 1} not match for {'a': 1}"
         assert len(e.errors) == 1
-        assert type(e.errors[0]) == LiteralInvalid
+        assert isinstance(e.errors[0], LiteralInvalid)
     else:
         assert False, "Did not raise Invalid"
 
@@ -184,7 +184,7 @@ class C1(object):
     except MultipleInvalid as e:
         assert str(e) == "expected C1"
         assert len(e.errors) == 1
-        assert type(e.errors[0]) == TypeInvalid
+        assert isinstance(e.errors[0], TypeInvalid)
     else:
         assert False, "Did not raise Invalid"
 
@@ -200,7 +200,7 @@ class C2:
     except MultipleInvalid as e:
         assert str(e) == "expected C2"
         assert len(e.errors) == 1
-        assert type(e.errors[0]) == TypeInvalid
+        assert isinstance(e.errors[0], TypeInvalid)
     else:
         assert False, "Did not raise Invalid"