Add support for registering with dependency and implementation being the same.

Author: runemalm

src/dependency_injection/container.py

@@ -29,17 +29,23 @@ def get_instance(cls, name: str=None) -> Self:
 
         return cls._instances[(cls, name)]
 
-    def register_transient(self, dependency: Type, implementation: Type, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+    def register_transient(self, dependency: Type, implementation: Optional[Type] = None, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+        if implementation is None:
+            implementation = dependency
         if dependency in self._registrations:
             raise ValueError(f"Dependency {dependency} is already registered.")
         self._registrations[dependency] = Registration(dependency, implementation, Scope.TRANSIENT, constructor_args)
 
-    def register_scoped(self, dependency: Type, implementation: Type, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+    def register_scoped(self, dependency: Type, implementation: Optional[Type] = None, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+        if implementation is None:
+            implementation = dependency
         if dependency in self._registrations:
             raise ValueError(f"Dependency {dependency} is already registered.")
         self._registrations[dependency] = Registration(dependency, implementation, Scope.SCOPED, constructor_args)
 
-    def register_singleton(self, dependency: Type, implementation: Type, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+    def register_singleton(self, dependency: Type, implementation: Optional[Type] = None, constructor_args: Optional[Dict[str, Any]] = None) -> None:
+        if implementation is None:
+            implementation = dependency
         if dependency in self._registrations:
             raise ValueError(f"Dependency {dependency} is already registered.")
         self._registrations[dependency] = Registration(dependency, implementation, Scope.SINGLETON, constructor_args)

tests/unit_test/container/register/test_register_scoped.py

@@ -44,3 +44,19 @@ class Car(Vehicle):
         # act + assert
         with pytest.raises(ValueError, match="is already registered"):
             dependency_container.register_scoped(dependency, implementation)
+
+    def test_register_scoped_when_dependency_and_implementation_being_the_same(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+
+        # act
+        dependency_container.register_scoped(dependency)
+
+        # assert (no exception thrown)
+

tests/unit_test/container/register/test_register_singleton.py

@@ -44,3 +44,18 @@ class Car(Vehicle):
         # act + assert
         with pytest.raises(ValueError, match="is already registered"):
             dependency_container.register_singleton(dependency, implementation)
+
+    def test_register_singleton_when_dependency_and_implementation_being_the_same(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+
+        # act
+        dependency_container.register_singleton(dependency)
+
+        # assert (no exception thrown)

tests/unit_test/container/register/test_register_transient.py

@@ -43,3 +43,18 @@ class Car(Vehicle):
         # act + assert
         with pytest.raises(ValueError, match="is already registered"):
             dependency_container.register_transient(dependency, implementation)
+
+    def test_register_transient_when_dependency_and_implementation_being_the_same(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+
+        # act
+        dependency_container.register_transient(dependency)
+
+        # assert (no exception thrown)

tests/unit_test/container/resolve/test_resolve_scoped.py

@@ -47,3 +47,21 @@ class Car(Vehicle):
 
         # assert
         self.assertNotEqual(resolved_dependency_in_scope_1, resolved_dependency_in_scope_2)
+
+    def test_resolve_scoped_when_registered_with_dependency_and_implementation_being_the_same_returns_an_instance(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+        dependency_container.register_scoped(dependency)
+
+        # act
+        resolved_dependency = dependency_container.resolve(dependency)
+
+        # assert
+        self.assertIsInstance(resolved_dependency, Vehicle)
+

tests/unit_test/container/resolve/test_resolve_singleton.py

@@ -46,3 +46,20 @@ class Car(Vehicle):
 
         # assert
         self.assertEqual(resolved_dependency_1, resolved_dependency_2)
+
+    def test_resolve_singleton_when_registered_with_dependency_and_implementation_being_the_same_returns_an_instance(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+        dependency_container.register_singleton(dependency)
+
+        # act
+        resolved_dependency = dependency_container.resolve(dependency)
+
+        # assert
+        self.assertIsInstance(resolved_dependency, Vehicle)

tests/unit_test/container/resolve/test_resolve_transient.py

@@ -46,3 +46,20 @@ class Car(Vehicle):
 
         # assert
         self.assertNotEqual(resolved_dependency_1, resolved_dependency_2)
+
+    def test_resolve_transient_when_registered_with_dependency_and_implementation_being_the_same_returns_an_instance(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency = Vehicle
+        dependency_container.register_transient(dependency)
+
+        # act
+        resolved_dependency = dependency_container.resolve(dependency)
+
+        # assert
+        self.assertIsInstance(resolved_dependency, Vehicle)