Fix wiring for @classmethod and @staticmethod

docs/main/changelog.rst

@@ -7,6 +7,11 @@ that were made in every particular version.
 From version 0.7.6 *Dependency Injector* framework strictly 
 follows `Semantic versioning`_
 
+Develop
+-------
+- Fix a bug in ``wiring`` with improper patching of ``@classmethod`` and ``@staticmethod`` decorated methods
+  (See issue `#318 <https://github.com/ets-labs/python-dependency-injector/issues/318>`_).
+
 4.3.2
 -----
 - Fix a bug in ``wiring`` with mistakenly initialized and shutdown resource with ``Closing``

src/dependency_injector/wiring.py

@@ -5,7 +5,7 @@ import inspect
 import pkgutil
 import sys
 from types import ModuleType
-from typing import Optional, Iterable, Callable, Any, Tuple, Dict, Generic, TypeVar, cast
+from typing import Optional, Iterable, Callable, Any, Tuple, Dict, Generic, TypeVar, Type, cast
 
 if sys.version_info < (3, 7):
     from typing import GenericMeta
@@ -176,7 +176,7 @@ def wire(
                 _patch_fn(module, name, member, providers_map)
             elif inspect.isclass(member):
                 for method_name, method in inspect.getmembers(member, _is_method):
-                    _patch_fn(member, method_name, method, providers_map)
+                    _patch_method(member, method_name, method, providers_map)
 
 
 def unwire(
@@ -195,10 +195,10 @@ def unwire(
     for module in modules:
         for name, member in inspect.getmembers(module):
             if inspect.isfunction(member):
-                _unpatch_fn(module, name, member)
+                _unpatch(module, name, member)
             elif inspect.isclass(member):
                 for method_name, method in inspect.getmembers(member, inspect.isfunction):
-                    _unpatch_fn(member, method_name, method)
+                    _unpatch(member, method_name, method)
 
 
 def _patch_fn(
@@ -210,10 +210,41 @@ def _patch_fn(
     injections, closing = _resolve_injections(fn, providers_map)
     if not injections:
         return
-    setattr(module, name, _patch_with_injections(fn, injections, closing))
+    patched = _patch_with_injections(fn, injections, closing)
+    setattr(module, name, _wrap_patched(patched, fn, injections, closing))
 
 
-def _unpatch_fn(
+def _patch_method(
+        cls: Type,
+        name: str,
+        method: Callable[..., Any],
+        providers_map: ProvidersMap,
+) -> None:
+    injections, closing = _resolve_injections(method, providers_map)
+    if not injections:
+        return
+
+    if hasattr(cls, '__dict__') \
+            and name in cls.__dict__ \
+            and isinstance(cls.__dict__[name], (classmethod, staticmethod)):
+        method = cls.__dict__[name]
+        patched = _patch_with_injections(method.__func__, injections, closing)
+        patched = type(method)(patched)
+    else:
+        patched = _patch_with_injections(method, injections, closing)
+
+    setattr(cls, name, _wrap_patched(patched, method, injections, closing))
+
+
+def _wrap_patched(patched: Callable[..., Any], original, injections, closing):
+    patched.__wired__ = True
+    patched.__original__ = original
+    patched.__injections__ = injections
+    patched.__closing__ = closing
+    return patched
+
+
+def _unpatch(
         module: ModuleType,
         name: str,
         fn: Callable[..., Any],
@@ -276,12 +307,6 @@ def _patch_with_injections(fn, injections, closing):
         _patched = _get_async_patched(fn, injections, closing)
     else:
         _patched = _get_patched(fn, injections, closing)
-
-    _patched.__wired__ = True
-    _patched.__original__ = fn
-    _patched.__injections__ = injections
-    _patched.__closing__ = closing
-
     return _patched
 
 

tests/unit/wiring/test_wiring_py36.py

@@ -65,10 +65,20 @@ class WiringTest(unittest.TestCase):
         service = module.TestClass.class_method()
         self.assertIsInstance(service, Service)
 
+    def test_instance_classmethod_wiring(self):
+        instance = module.TestClass()
+        service = instance.class_method()
+        self.assertIsInstance(service, Service)
+
     def test_class_staticmethod_wiring(self):
         service = module.TestClass.static_method()
         self.assertIsInstance(service, Service)
 
+    def test_instance_staticmethod_wiring(self):
+        instance = module.TestClass()
+        service = instance.static_method()
+        self.assertIsInstance(service, Service)
+
     def test_function_wiring(self):
         service = module.test_function()
         self.assertIsInstance(service, Service)