Allow annotated in classes (#263)

* Allow annotated in classes

---------

Co-authored-by: Filip Nešťák <filip@trendis.sk>
Co-authored-by: David Pärsson <david@parsson.se>

Author: 3 people

injector/__init__.py

@@ -1208,6 +1208,11 @@ def _is_new_union_type(instance: Any) -> bool:
         new_union_type = getattr(types, 'UnionType', None)
         return new_union_type is not None and isinstance(instance, new_union_type)
 
+    def _is_injection_annotation(annotation: Any) -> bool:
+        return _is_specialization(annotation, Annotated) and (
+            _inject_marker in annotation.__metadata__ or _noinject_marker in annotation.__metadata__
+        )
+
     spec = inspect.getfullargspec(callable)
 
     try:
@@ -1238,7 +1243,8 @@ def _is_new_union_type(instance: Any) -> bool:
         bindings.pop(spec.varkw, None)
 
     for k, v in list(bindings.items()):
-        if _is_specialization(v, Annotated):
+        # extract metadata only from Inject and NonInject
+        if _is_injection_annotation(v):
             v, metadata = v.__origin__, v.__metadata__
             bindings[k] = v
         else:

injector_test.py

@@ -11,6 +11,7 @@
 """Functional tests for the "Injector" dependency injection framework."""
 
 from contextlib import contextmanager
+from dataclasses import dataclass
 from typing import Any, NewType, Optional, Union
 import abc
 import sys
@@ -1754,3 +1755,53 @@ def configure(binder):
     injector = Injector([configure])
     assert injector.get(foo) == 123
     assert injector.get(bar) == 456
+
+
+def test_annotated_integration_with_annotated():
+    UserID = Annotated[int, 'user_id']
+
+    @inject
+    class TestClass:
+        def __init__(self, user_id: UserID):
+            self.user_id = user_id
+
+    def configure(binder):
+        binder.bind(UserID, to=123)
+
+    injector = Injector([configure])
+
+    test_class = injector.get(TestClass)
+    assert test_class.user_id == 123
+
+
+def test_newtype_integration_with_annotated():
+    UserID = NewType('UserID', int)
+
+    @inject
+    class TestClass:
+        def __init__(self, user_id: UserID):
+            self.user_id = user_id
+
+    def configure(binder):
+        binder.bind(UserID, to=123)
+
+    injector = Injector([configure])
+
+    test_class = injector.get(TestClass)
+    assert test_class.user_id == 123
+
+
+def test_dataclass_annotated_parameter():
+    Foo = Annotated[int, object()]
+
+    def configure(binder):
+        binder.bind(Foo, to=123)
+
+    @inject
+    @dataclass
+    class MyClass:
+        foo: Foo
+
+    injector = Injector([configure])
+    instance = injector.get(MyClass)
+    assert instance.foo == 123