Support injecting annotated types with Inject[] (#279)

* Support injecting annotated types with `Inject[]`

This was missing in #263.

* Extend the tests with two annotated types

To avoid the test from passing by just binding the origin type.

* Disable branch coverage

`__metadata__` is never empty.

Author: davidparsson

injector/__init__.py

@@ -1213,6 +1213,16 @@ def _is_injection_annotation(annotation: Any) -> bool:
             _inject_marker in annotation.__metadata__ or _noinject_marker in annotation.__metadata__
         )
 
+    def _recreate_annotated_origin(annotated_type: Any) -> Any:
+        # Creates `Annotated[type, annotation]` from `Inject[Annotated[type, annotation]]`,
+        # to support the injection of annotated types with the `Inject[]` annotation.
+        origin = annotated_type.__origin__
+        for metadata in annotated_type.__metadata__:  # pragma: no branch
+            if metadata in (_inject_marker, _noinject_marker):
+                break
+            origin = Annotated[origin, metadata]
+        return origin
+
     spec = inspect.getfullargspec(callable)
 
     try:
@@ -1245,7 +1255,7 @@ def _is_injection_annotation(annotation: Any) -> bool:
     for k, v in list(bindings.items()):
         # extract metadata only from Inject and NonInject
         if _is_injection_annotation(v):
-            v, metadata = v.__origin__, v.__metadata__
+            v, metadata = _recreate_annotated_origin(v), v.__metadata__
             bindings[k] = v
         else:
             metadata = tuple()

injector_test.py

@@ -1700,6 +1700,67 @@ def function(a: int) -> 'InvalidForwardReference':
     assert get_bindings(function) == {'a': int}
 
 
+def test_gets_bindings_for_annotated_type_with_inject_decorator() -> None:
+    UserID = Annotated[int, 'user_id']
+
+    @inject
+    def function(a: UserID, b: str) -> None:
+        pass
+
+    assert get_bindings(function) == {'a': UserID, 'b': str}
+
+
+def test_gets_bindings_of_annotated_type_with_inject_annotation() -> None:
+    UserID = Annotated[int, 'user_id']
+
+    def function(a: Inject[UserID], b: Inject[str]) -> None:
+        pass
+
+    assert get_bindings(function) == {'a': UserID, 'b': str}
+
+
+def test_gets_bindings_of_new_type_with_inject_annotation() -> None:
+    Name = NewType('Name', str)
+
+    @inject
+    def function(a: Name, b: str) -> None:
+        pass
+
+    assert get_bindings(function) == {'a': Name, 'b': str}
+
+
+def test_gets_bindings_of_inject_annotation_with_new_type() -> None:
+    def function(a: Inject[Name], b: str) -> None:
+        pass
+
+    assert get_bindings(function) == {'a': Name}
+
+
+def test_get_bindings_of_nested_noinject_inject_annotation() -> None:
+    # This is not how this is intended to be used
+    def function(a: Inject[NoInject[int]], b: NoInject[Inject[str]]) -> None:
+        pass
+
+    assert get_bindings(function) == {}
+
+
+def test_get_bindings_of_nested_noinject_inject_annotation_and_inject_decorator() -> None:
+    # This is not how this is intended to be used
+    @inject
+    def function(a: Inject[NoInject[int]], b: NoInject[Inject[str]]) -> None:
+        pass
+
+    assert get_bindings(function) == {}
+
+
+def test_get_bindings_of_nested_inject_annotations() -> None:
+    # This is not how this is intended to be used
+    def function(a: Inject[Inject[int]]) -> None:
+        pass
+
+    assert get_bindings(function) == {'a': int}
+
+
 # Tests https://github.com/alecthomas/injector/issues/202
 @pytest.mark.skipif(sys.version_info < (3, 10), reason="Requires Python 3.10+")
 def test_get_bindings_for_pep_604():
@@ -1785,21 +1846,80 @@ def configure(binder):
 
 def test_annotated_integration_with_annotated():
     UserID = Annotated[int, 'user_id']
+    UserAge = Annotated[int, 'user_age']
 
     @inject
     class TestClass:
-        def __init__(self, user_id: UserID):
+        def __init__(self, user_id: UserID, user_age: UserAge):
+            self.user_id = user_id
+            self.user_age = user_age
+
+    def configure(binder):
+        binder.bind(UserID, to=123)
+        binder.bind(UserAge, to=32)
+
+    injector = Injector([configure])
+
+    test_class = injector.get(TestClass)
+    assert test_class.user_id == 123
+    assert test_class.user_age == 32
+
+
+def test_inject_annotation_with_annotated_type():
+    UserID = Annotated[int, 'user_id']
+    UserAge = Annotated[int, 'user_age']
+
+    class TestClass:
+        def __init__(self, user_id: Inject[UserID], user_age: Inject[UserAge]):
             self.user_id = user_id
+            self.user_age = user_age
 
     def configure(binder):
         binder.bind(UserID, to=123)
+        binder.bind(UserAge, to=32)
+        binder.bind(int, to=456)
+
+    injector = Injector([configure])
+
+    test_class = injector.get(TestClass)
+    assert test_class.user_id == 123
+    assert test_class.user_age == 32
+
+
+def test_inject_annotation_with_nested_annotated_type():
+    UserID = Annotated[int, 'user_id']
+    SpecialUserID = Annotated[UserID, 'special_user_id']
+
+    class TestClass:
+        def __init__(self, user_id: Inject[SpecialUserID]):
+            self.user_id = user_id
+
+    def configure(binder):
+        binder.bind(SpecialUserID, to=123)
 
     injector = Injector([configure])
 
     test_class = injector.get(TestClass)
     assert test_class.user_id == 123
 
 
+def test_noinject_annotation_with_annotated_type():
+    UserID = Annotated[int, 'user_id']
+
+    @inject
+    class TestClass:
+        def __init__(self, user_id: NoInject[UserID] = None):
+            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 is None
+
+
 def test_newtype_integration_with_annotated():
     UserID = NewType('UserID', int)
 
@@ -1817,6 +1937,22 @@ def configure(binder):
     assert test_class.user_id == 123
 
 
+def test_newtype_with_injection_annotation():
+    UserID = NewType('UserID', int)
+
+    class TestClass:
+        def __init__(self, user_id: Inject[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()]