✨ refactor: lift dependency injection to main and add documentation f…

…or its role

           - Moved dependency injection from `MyApp` to `main` to align with Onion Architecture principles.
           - Updated `MyApp` to receive injected dependencies through its constructor.
           - Added Dartdoc to the `main` function explaining its role as the entry point and dependency injector in the outermost circle of the architecture.

Signed-off-by: Dmytro Turskyi <[email protected]>

.gitignore

@@ -41,3 +41,4 @@ app.*.map.json
 /android/app/debug
 /android/app/profile
 /android/app/release
+/coverage/

README.md

@@ -29,7 +29,7 @@ using [streams](https://dart.dev/libraries/async/using-streams).
 
 The project follows the four main layers of Onion Architecture:
 
-1. **Domain Model**: Core business logic and entities.
+1. **Domain Model**: Core business logic and models.
 2. **Domain Services**: Business rules and operations.
 3. **Application Services**: Application-specific logic and orchestration.
 4. **Outermost Layer**: Includes User Interface, Infrastructure (DB and/or WS),
@@ -253,27 +253,34 @@ class _MyHomePageState extends State<MyHomePage> {
 }
 
 class MyApp extends StatelessWidget {
-  const MyApp({super.key});
+  const MyApp({required this.presenter, super.key});
+
+  final CounterPresenter presenter;
 
   @override
   Widget build(BuildContext context) {
-    final FakeCounterDataSource dataSource = FakeCounterDataSource();
-    final IncrementCounterFakeImpl incrementCounter =
-    IncrementCounterFakeImpl(dataSource);
-    final CounterPresenter presenter = CounterPresenter(incrementCounter);
-
     return MaterialApp(
-      title: 'Flutter Demo',
+      title: 'Flutter Onion Architecture Demo',
       debugShowCheckedModeBanner: false,
       theme: ThemeData(
         colorSchemeSeed: Colors.blue,
       ),
-      home: MyHomePage(title: 'Flutter Demo Home Page', presenter: presenter),
+      home: MyHomePage(
+        title: 'Onion Architecture Demo Home Page',
+        presenter: presenter,
+      ),
     );
   }
 }
 
-void main() => runApp(const MyApp());
+void main() {
+  final FakeCounterDataSource dataSource = FakeCounterDataSource();
+  final IncrementCounter incrementCounter = IncrementCounterFakeImpl(
+    dataSource,
+  );
+  final CounterPresenter presenter = CounterPresenter(incrementCounter);
+  runApp(MyApp(presenter: presenter));
+}
 
 // Infrastructure Component
 abstract interface class CounterDataSource {

lib/main.dart

@@ -1,16 +1,28 @@
+import 'package:counter_with_onion_architecture/core/application_services/counter_presenter.dart';
+import 'package:counter_with_onion_architecture/core/domain/services/increment_counter.dart';
+import 'package:counter_with_onion_architecture/core/domain/services/increment_counter_fake_impl.dart';
+import 'package:counter_with_onion_architecture/infrastructure/fake_counter_data_source.dart';
 import 'package:counter_with_onion_architecture/user_interface/my_app.dart';
 import 'package:flutter/material.dart';
 
-/// The [main] is the ultimate detail — the lowest-level policy.
-/// It is the initial entry point of the system.
-/// Nothing, other than the operating system, depends on it.
-/// It is in this [main] component that dependencies should be injected.
-/// The [main] is a dirty low-level module in the outermost circle of the onion
-/// architecture.
-/// Think of [main] as a plugin to the [MyApp] — a plugin that sets up the
-/// initial conditions and configurations, gathers all the outside resources,
-/// and then hands control over to the high-level policy of the [MyApp].
-/// When [main] is released, it has utterly no effect on any of the other
-/// components in the system. They don’t know about [main], and they don’t care
-/// when it changes.
-void main() => runApp(const MyApp());
+/// The [main] function represents the ultimate detail — the lowest-level policy
+/// in the system.
+/// It serves as the initial entry point of the application, and nothing, other
+/// than the operating system, depends on it.
+/// In the [main] function, dependencies are injected and configurations are
+/// set up.
+/// This makes [main] a low-level module located in the outermost circle of the
+/// onion architecture.
+/// Think of [main] as a plugin to the application — a module that gathers all
+/// external resources, sets initial conditions, and hands control over to the
+/// high-level policy represented by [MyApp].
+/// Changes to [main] do not affect any other component in the system, as they
+/// are decoupled from it and remain unaffected by its modifications.
+void main() {
+  final FakeCounterDataSource dataSource = FakeCounterDataSource();
+  final IncrementCounter incrementCounter = IncrementCounterFakeImpl(
+    dataSource,
+  );
+  final CounterPresenter presenter = CounterPresenter(incrementCounter);
+  runApp(MyApp(presenter: presenter));
+}

lib/user_interface/my_app.dart

@@ -1,20 +1,14 @@
 import 'package:counter_with_onion_architecture/core/application_services/counter_presenter.dart';
-import 'package:counter_with_onion_architecture/core/domain/services/increment_counter.dart';
-import 'package:counter_with_onion_architecture/core/domain/services/increment_counter_fake_impl.dart';
-import 'package:counter_with_onion_architecture/infrastructure/fake_counter_data_source.dart';
 import 'package:counter_with_onion_architecture/user_interface/my_home_page.dart';
 import 'package:flutter/material.dart';
 
 class MyApp extends StatelessWidget {
-  const MyApp({super.key});
+  const MyApp({required this.presenter, super.key});
+
+  final CounterPresenter presenter;
 
   @override
   Widget build(BuildContext context) {
-    final FakeCounterDataSource dataSource = FakeCounterDataSource();
-    final IncrementCounter incrementCounter =
-        IncrementCounterFakeImpl(dataSource);
-    final CounterPresenter presenter = CounterPresenter(incrementCounter);
-
     return MaterialApp(
       title: 'Flutter Onion Architecture Demo',
       debugShowCheckedModeBanner: false,

pubspec.lock

@@ -58,10 +58,10 @@ packages:
     dependency: "direct dev"
     description:
       name: flutter_lints
-      sha256: "3f41d009ba7172d5ff9be5f6e6e6abb4300e263aab8866d2a0842ed2a70f8f0c"
+      sha256: "5398f14efa795ffb7a33e9b6a08798b26a180edac4ad7db3f231e40f82ce11e1"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "5.0.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -71,18 +71,18 @@ packages:
     dependency: transitive
     description:
       name: leak_tracker
-      sha256: "7f0df31977cb2c0b88585095d168e689669a2cc9b97c309665e3386f3e9d341a"
+      sha256: "3f87a60e8c63aecc975dda1ceedbc8f24de75f09e4856ea27daf8958f2f0ce05"
       url: "https://pub.dev"
     source: hosted
-    version: "10.0.4"
+    version: "10.0.5"
   leak_tracker_flutter_testing:
     dependency: transitive
     description:
       name: leak_tracker_flutter_testing
-      sha256: "06e98f569d004c1315b991ded39924b21af84cf14cc94791b8aea337d25b57f8"
+      sha256: "932549fb305594d82d7183ecd9fa93463e9914e1b67cacc34bc40906594a1806"
       url: "https://pub.dev"
     source: hosted
-    version: "3.0.3"
+    version: "3.0.5"
   leak_tracker_testing:
     dependency: transitive
     description:
@@ -95,10 +95,10 @@ packages:
     dependency: transitive
     description:
       name: lints
-      sha256: "976c774dd944a42e83e2467f4cc670daef7eed6295b10b36ae8c85bcbf828235"
+      sha256: "3315600f3fb3b135be672bf4a178c55f274bebe368325ae18462c89ac1e3b413"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "5.0.0"
   matcher:
     dependency: transitive
     description:
@@ -111,18 +111,18 @@ packages:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
+      sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
       url: "https://pub.dev"
     source: hosted
-    version: "0.8.0"
+    version: "0.11.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "7687075e408b093f36e6bbf6c91878cc0d4cd10f409506f7bc996f68220b9136"
+      sha256: bdb68674043280c3428e9ec998512fb681678676b3c54e773629ffe74419f8c7
       url: "https://pub.dev"
     source: hosted
-    version: "1.12.0"
+    version: "1.15.0"
   path:
     dependency: transitive
     description:
@@ -180,10 +180,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "9955ae474176f7ac8ee4e989dadfb411a58c30415bcfb648fa04b2b8a03afa7f"
+      sha256: "5b8a98dafc4d5c4c9c72d8b31ab2b23fc13422348d2997120294d3bac86b4ddb"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.0"
+    version: "0.7.2"
   vector_math:
     dependency: transitive
     description:
@@ -196,10 +196,10 @@ packages:
     dependency: transitive
     description:
       name: vm_service
-      sha256: "3923c89304b715fb1eb6423f017651664a03bf5f4b29983627c4da791f74a4ec"
+      sha256: "5c5f338a667b4c644744b661f309fb8080bb94b18a7e91ef1dbd343bed00ed6d"
       url: "https://pub.dev"
     source: hosted
-    version: "14.2.1"
+    version: "14.2.5"
 sdks:
-  dart: ">=3.4.3 <4.0.0"
+  dart: ">=3.5.0 <4.0.0"
   flutter: ">=3.18.0-18.0.pre.54"

pubspec.yaml

@@ -45,7 +45,7 @@ dev_dependencies:
   # activated in the `analysis_options.yaml` file located at the root of your
   # package. See that file for information about deactivating specific lint
   # rules and activating additional ones.
-  flutter_lints: ^4.0.0
+  flutter_lints: ^5.0.0
 
   flutter_test:
     sdk: flutter

test/widget_test.dart

@@ -1,11 +1,20 @@
+import 'package:counter_with_onion_architecture/core/application_services/counter_presenter.dart';
+import 'package:counter_with_onion_architecture/core/domain/services/increment_counter.dart';
+import 'package:counter_with_onion_architecture/core/domain/services/increment_counter_fake_impl.dart';
+import 'package:counter_with_onion_architecture/infrastructure/fake_counter_data_source.dart';
 import 'package:counter_with_onion_architecture/user_interface/my_app.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   testWidgets('Counter increments smoke test', (WidgetTester tester) async {
+    final FakeCounterDataSource dataSource = FakeCounterDataSource();
+    final IncrementCounter incrementCounter = IncrementCounterFakeImpl(
+      dataSource,
+    );
+    final CounterPresenter presenter = CounterPresenter(incrementCounter);
     // Build our app and trigger a frame.
-    await tester.pumpWidget(const MyApp());
+    await tester.pumpWidget(MyApp(presenter: presenter));
 
     // Verify that our counter starts at 0.
     expect(find.text('0'), findsOneWidget);