Update provider overriding example to use container and fix bug

examples/providers/overriding.py

@@ -1,8 +1,9 @@
 """Simple providers overriding example."""
 
+import dataclasses
 import unittest.mock
 
-from dependency_injector import providers
+from dependency_injector import containers, providers
 
 
 class ApiClient:
@@ -13,30 +14,35 @@ class ApiClientStub(ApiClient):
     ...
 
 
+@dataclasses.dataclass
 class Service:
-    def __init__(self, api_client: ApiClient):
-        self._api_client = api_client
+    api_client: ApiClient
 
 
-api_client_factory = providers.Factory(ApiClient)
-service_factory = providers.Factory(
-    Service,
-    api_client=api_client_factory,
-)
+class Container(containers.DeclarativeContainer):
+
+    api_client_factory = providers.Factory(ApiClient)
+
+    service_factory = providers.Factory(
+        Service,
+        api_client=api_client_factory,
+    )
 
 
 if __name__ == '__main__':
+    container = Container()
+
     # 1. Use .override() to replace the API client with stub
-    api_client_factory.override(providers.Factory(ApiClientStub))
-    service1 = service_factory()
+    container.api_client_factory.override(providers.Factory(ApiClientStub))
+    service1 = container.service_factory()
     assert isinstance(service1.api_client, ApiClientStub)
 
     # 2. Use .override() as a context manager to mock the API client in testing
-    with api_client_factory.override(unittest.mock.Mock(ApiClient)):
-        service3 = service_factory()
-        assert isinstance(service3.api_client, unittest.mock.Mock)
+    with container.api_client_factory.override(unittest.mock.Mock(ApiClient)):
+        service2 = container.service_factory()
+        assert isinstance(service2.api_client, unittest.mock.Mock)
 
     # 3. Use .reset_override() to get back to normal
-    api_client_factory.reset_override()
-    service3 = service_factory()
+    container.api_client_factory.reset_override()
+    service3 = container.service_factory()
     assert isinstance(service3.api_client, ApiClient)