Add typing tests

src/dependency_injector/providers.pyi

@@ -13,7 +13,9 @@ from typing import (
     Optional,
     Union,
     Coroutine as _Coroutine,
+    Iterator as _Iterator,
     Generator as _Generator,
+    overload,
 )
 
 from . import resources
@@ -278,16 +280,12 @@ class Dict(Provider):
 
 
 class Resource(Provider, Generic[T]):
-    def __init__(
-            self,
-            initializer: Union[
-                resources.Resource,
-                _Generator[T, ..., ...],
-                _Callable[..., T],
-            ],
-            *args: Injection,
-            **kwargs: Injection,
-    ): ...
+    @overload
+    def __init__(self, initializer: _Callable[..., resources.Resource[T]], *args: Injection, **kwargs: Injection) -> None: ...
+    @overload
+    def __init__(self, initializer: _Callable[..., _Iterator[T]], *args: Injection, **kwargs: Injection) -> None: ...
+    @overload
+    def __init__(self, initializer: _Callable[..., T], *args: Injection, **kwargs: Injection) -> None: ...
     def __call__(self, *args: Injection, **kwargs: Injection) -> T: ...
     @property
     def args(self) -> Tuple[Injection]: ...

src/dependency_injector/resources.py

@@ -2,7 +2,7 @@
 
 import abc
 import sys
-from typing import Generic, TypeVar
+from typing import TypeVar, Generic
 
 if sys.version_info < (3, 7):
     from typing import GenericMeta

tests/typing/resource.py

@@ -0,0 +1,43 @@
+from typing import List, Iterator, Generator
+
+from dependency_injector import providers, resources
+
+
+# Test 1: to check the return type with function
+def init1() -> List[int]:
+    return []
+
+
+provider1 = providers.Resource(init1)
+var1: List[int] = provider1()
+
+
+# Test 2: to check the return type with iterator
+def init2() -> Iterator[List[int]]:
+    yield []
+
+
+provider2 = providers.Resource(init2)
+var2: List[int] = provider2()
+
+
+# Test 3: to check the return type with generator
+def init3() -> Generator[List[int], None, None]:
+    yield []
+
+
+provider3 = providers.Resource(init3)
+var3: List[int] = provider3()
+
+
+# Test 4: to check the return type with resource subclass
+class MyResource4(resources.Resource[List[int]]):
+    def init(self, *args, **kwargs) -> List[int]:
+        return []
+
+    def shutdown(self, resource: List[int]) -> None:
+        ...
+
+
+provider4 = providers.Resource(MyResource4)
+var4: List[int] = provider4()