Fix deep_iterable, deep_mapping validator type stubs (#533)

Use bound type variables for iterables and mappings of the validated item types, so mypy does not erroneously require both the iterable attribute validated by deep_iterable and the item type validated by the first argument of deep_iterable to have the same type. This fixes #531.

changelog.d/533.change.rst

@@ -0,0 +1,2 @@
+Fixed ``attr.validators.deep_iterable()``
+and ``attr.validators.deep_mapping()`` type stubs.

src/attr/validators.pyi

@@ -1,7 +1,22 @@
-from typing import Container, List, Union, TypeVar, Type, Any, Optional, Tuple
+from typing import (
+    Container,
+    List,
+    Union,
+    TypeVar,
+    Type,
+    Any,
+    Optional,
+    Tuple,
+    Iterable,
+    Mapping,
+)
 from . import _ValidatorType
 
 _T = TypeVar("_T")
+_I = TypeVar("_I", bound=Iterable[_T])
+_K = TypeVar("_K")
+_V = TypeVar("_V")
+_M = TypeVar("_V", bound=Mapping[_K, _V])
 
 def instance_of(
     type: Union[Tuple[Type[_T], ...], Type[_T]]
@@ -14,11 +29,11 @@ def in_(options: Container[_T]) -> _ValidatorType[_T]: ...
 def and_(*validators: _ValidatorType[_T]) -> _ValidatorType[_T]: ...
 def deep_iterable(
     member_validator: _ValidatorType[_T],
-    iterable_validator: Optional[_ValidatorType[_T]],
-) -> _ValidatorType[_T]: ...
+    iterable_validator: Optional[_ValidatorType[_I]] = ...,
+) -> _ValidatorType[_I]: ...
 def deep_mapping(
-    key_validator: _ValidatorType[_T],
-    value_validator: _ValidatorType[_T],
-    mapping_validator: Optional[_ValidatorType[_T]],
-) -> _ValidatorType[_T]: ...
+    key_validator: _ValidatorType[_K],
+    value_validator: _ValidatorType[_V],
+    mapping_validator: Optional[_ValidatorType[_M]] = ...,
+) -> _ValidatorType[_M]: ...
 def is_callable() -> _ValidatorType[_T]: ...

tests/typing_example.py

@@ -1,4 +1,4 @@
-from typing import Any, List
+from typing import Any, Dict, List, Tuple
 
 import attr
 
@@ -114,3 +114,40 @@ except Error as e:
 
 # ConvCDefaultIfNone(1)
 # ConvCDefaultIfNone(None)
+
+
+# Validators
+@attr.s
+class Validated:
+    a = attr.ib(
+        type=List[C],
+        validator=attr.validators.deep_iterable(
+            attr.validators.instance_of(C), attr.validators.instance_of(list)
+        ),
+    )
+    a = attr.ib(
+        type=Tuple[C],
+        validator=attr.validators.deep_iterable(
+            attr.validators.instance_of(C), attr.validators.instance_of(tuple)
+        ),
+    )
+    b = attr.ib(
+        type=List[C],
+        validator=attr.validators.deep_iterable(
+            attr.validators.instance_of(C)
+        ),
+    )
+    c = attr.ib(
+        type=Dict[C, D],
+        validator=attr.validators.deep_mapping(
+            attr.validators.instance_of(C),
+            attr.validators.instance_of(D),
+            attr.validators.instance_of(dict),
+        ),
+    )
+    d = attr.ib(
+        type=Dict[C, D],
+        validator=attr.validators.deep_mapping(
+            attr.validators.instance_of(C), attr.validators.instance_of(D)
+        ),
+    )