Move bloc related APIs to comms package (#60)

* Move bloc related APIs to comms package

- update changelog and pubspec version

- add bloc package

- add ListenerBloc, ListenerCubit and StateSender

- add tests

- extract ProductCountChangedMessage to seperate file

Related to #59

* Update README

packages/comms/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.1
+
+- Move bloc related apis from flutter_comms package and update README (#60)
+
 ## 1.0.0
 
 - Introduce covariant listening by filtering `Listener`s contravariantly (#58)

packages/comms/README.md

@@ -102,6 +102,8 @@ void main() async {
   print(lightBulbB.enabled); // false
 
   lightSwitchB.enable();
+  
+  await Future<void>.delayed(Duration.zero);
 
   print(lightBulbA.enabled); // true
   print(lightBulbB.enabled); // true
@@ -204,6 +206,90 @@ void main() {
 }
 ```
 
+## Communicating between blocs
+
+To communicate between blocs you can just use `Sender` and `Listener` mixins, for 
+more convenience there are added `ListenerCubit` or `ListenerBloc` classes and 
+`StateSender` mixin.
+
+### Creating a ListenerCubit
+
+A `ListenerCubit` works exactly like `Listener` but calls `listen` and `cancel`
+functions for you, enabling your `Cubit` to receive messages from any `Sender`
+sharing the same message type.
+
+```dart
+/// Use `ListenerCubit` instead of `Cubit`, second type parameter specifies
+/// message type to listen for.
+class LightBulbCubit with ListenerCubit<LightBulbState, LightSwitchState> {
+  LightBulbCubit() : super(LightBulbState(false));
+  
+  /// Override `onMessage` to specify how to react to messages.
+  @override
+  void onMessage(LightSwitchState message) {
+    if (message is LightSwitchEnabled) {
+      emit(LightBulbState(true));
+    } else if (message is LightSwitchDisabled) {
+      emit(LightBulbState(false));
+    }
+  }
+}
+
+class LightBulbState {
+  LightBulbState(this.enabled)
+  final bool enabled;
+}
+```
+
+### Creating a StateSender
+A `StateSender` mixin allows your bloc to send message with state every time a
+new state is emitted.
+
+```dart
+/// Add a `Sender` mixin with type of messages to send.
+class LightSwitchBloc extends Bloc<bool, LightSwitchState> 
+  with StateSender {
+  LightSwitchBloc() : super(false) {
+    on<bool>(
+      (event, emit) {
+        if (event) {
+          emit(LightSwitchEnabled());
+        } else {
+          emit(LightSwitchDisabled());
+        }
+      }
+    )
+  };
+}
+
+abstract class LightSwitchState {}
+class LightSwitchEnabled extends LightSwitchState {}
+class LightSwitchDisabled extends LightSwitchState {}
+```
+
+### Using ListenerCubit and StateSender
+
+```dart
+void main() async {
+  // Just create instances of both classes, comms will 
+  // handle connection between them.
+  final lightBulbCubit = LightBulCubit();
+  final lightSwitchBloc = LightSwitchBloc();
+
+  print(lightBulbCubit.state.enabled); // false
+
+  lightSwitchBloc.add(true);
+    
+  await Future<void>.delayed(Duration.zero);
+
+  print(lightBulbCubit.state.enabled); // true
+
+  // comms will automatically clean up resources on close
+  lightBulbCubit.close();
+  lightSwitchBloc.close();
+}
+```
+
 [pub_badge_style]: https://img.shields.io/badge/style-leancode__lint-black
 [pub_badge_link]: https://pub.dartlang.org/packages/leancode_lint
 [flutter_comms]: https://pub.dev/packages/flutter_comms

packages/comms/lib/comms.dart

@@ -1,11 +1,15 @@
 library comms;
 
 import 'dart:async';
-
+import 'package:bloc/bloc.dart';
 import 'package:logging/logging.dart';
-import 'package:meta/meta.dart' show nonVirtual, protected, visibleForTesting;
+import 'package:meta/meta.dart'
+    show mustCallSuper, nonVirtual, protected, visibleForTesting;
 
 part 'src/listener.dart';
 part 'src/message_sink_register.dart';
 part 'src/sender.dart';
 part 'src/multi_listener.dart';
+part 'src/bloc/listener_bloc.dart';
+part 'src/bloc/listener_cubit.dart';
+part 'src/bloc/state_sender.dart';

packages/comms/lib/src/bloc/listener_bloc.dart

@@ -0,0 +1,27 @@
+part of '../../comms.dart';
+
+/// Handles [Listener]'s [listen] and [close].
+///
+/// If your bloc needs to extend another class use [Listener] mixin.
+///
+/// Type argument [Message] marks what type of messages can be received.
+///
+/// See also:
+///
+///  * ListenerCubit, a class extending [Cubit] which handles calling [listen]
+/// and [cancel] automatically.
+///  * useMessageListener, a hook that provides [Listener]'s functionality
+/// which handles calling [listen] and [cancel] automatically.
+abstract class ListenerBloc<Event, State, Message> extends Bloc<Event, State>
+    with Listener<Message> {
+  ListenerBloc(super.initialState) {
+    super.listen();
+  }
+
+  @override
+  @mustCallSuper
+  Future<void> close() {
+    super.cancel();
+    return super.close();
+  }
+}

packages/comms/lib/src/bloc/listener_cubit.dart

@@ -0,0 +1,29 @@
+part of '../../comms.dart';
+
+/// Handles [Listener]'s [listen] and [close].
+///
+/// Use instead of [Cubit].
+///
+/// If your cubit needs to extend another class use [Listener] mixin.
+///
+/// Type argument [Message] marks what type of messages can be received.
+///
+/// See also:
+///
+///  * ListenerBloc, a class extending [Bloc] which handles calling [listen]
+/// and [cancel] automatically.
+///  * useMessageListener, a hook that provides [Listener]'s functionality
+/// which handles calling [listen] and [cancel] automatically.
+abstract class ListenerCubit<State, Message> extends Cubit<State>
+    with Listener<Message> {
+  ListenerCubit(super.initialState) {
+    super.listen();
+  }
+
+  @override
+  @mustCallSuper
+  Future<void> close() {
+    super.cancel();
+    return super.close();
+  }
+}

packages/comms/lib/src/bloc/state_sender.dart

@@ -0,0 +1,11 @@
+part of '../../comms.dart';
+
+/// Sends emitted [State]s to all [Listener]s of type [State].
+mixin StateSender<State> on BlocBase<State> {
+  @override
+  @mustCallSuper
+  void onChange(Change<State> change) {
+    super.onChange(change);
+    getSend<State>()(change.nextState);
+  }
+}

packages/comms/pubspec.yaml

@@ -1,12 +1,13 @@
 name: comms
 description: Simple communication pattern abstraction on streams, created for communication between logic classes.
-version: 1.0.0
+version: 1.0.1
 homepage: https://github.com/leancodepl/comms
 
 environment:
   sdk: ">=3.0.0 <4.0.0"
 
 dependencies:
+  bloc: ^8.1.2
   logging: ^1.2.0
   meta: ^1.9.1
 

packages/comms/test/comms_test.dart

@@ -2,7 +2,10 @@ import 'package:comms/comms.dart';
 import 'package:test/test.dart';
 
 import 'listeners/product_count.dart';
+import 'listeners/product_count_cubit.dart';
+import 'messages/product_count_changed.dart';
 import 'senders/basket.dart';
+import 'senders/basket_cubit.dart';
 
 int numberOfProductCountMessageSink() =>
     MessageSinkRegister().getSinksOfType<ProductCountChangedMessage>().length;
@@ -151,4 +154,71 @@ void main() {
       productCount.dispose();
     },
   );
+
+  group('ListenerCubit - Sender:', () {
+    test(
+      'ProductCountListenerCubit message sink is added to register after constructor',
+      () async {
+        final cubit = ProductCountListenerCubit();
+        expect(numberOfProductCountMessageSink(), 1);
+        await cubit.close();
+      },
+    );
+
+    test(
+      'ProductCountListenerCubit message sink is removed from register after close',
+      () async {
+        final cubit = ProductCountListenerCubit();
+        expect(numberOfProductCountMessageSink(), 1);
+        await cubit.close();
+        expect(numberOfProductCountMessageSink(), 0);
+      },
+    );
+
+    test(
+      'ProductCountListenerCubit state is consistent with number of elements in BasketCubit state',
+      () async {
+        final basketCubit = BasketCubit();
+        final productCountCubit = ProductCountListenerCubit();
+
+        basketCubit
+          ..add('T-shirt')
+          ..add('Socks');
+        await Future<void>.delayed(Duration.zero);
+
+        expect(productCountCubit.state, basketCubit.state.length);
+
+        basketCubit.removeLast();
+        await Future<void>.delayed(Duration.zero);
+
+        expect(productCountCubit.state, basketCubit.state.length);
+
+        await basketCubit.close();
+        await productCountCubit.close();
+      },
+    );
+
+    test(
+      'ProductCountListenerCubit correctly sets initial state using buffered message',
+      () async {
+        final basketCubit = BasketCubit()..add('Jeans');
+        final productCountCubit = ProductCountListenerCubit();
+
+        basketCubit
+          ..add('T-shirt')
+          ..add('Socks');
+        await Future<void>.delayed(Duration.zero);
+
+        expect(productCountCubit.state, basketCubit.state.length);
+
+        basketCubit.removeLast();
+        await Future<void>.delayed(Duration.zero);
+
+        expect(productCountCubit.state, basketCubit.state.length);
+
+        await basketCubit.close();
+        await productCountCubit.close();
+      },
+    );
+  });
 }

packages/comms/test/listeners/product_count.dart

@@ -1,5 +1,7 @@
 import 'package:comms/comms.dart';
 
+import '../messages/product_count_changed.dart';
+
 class ProductCount with Listener<ProductCountChangedMessage> {
   ProductCount() {
     listen();
@@ -55,9 +57,3 @@ class ProductCountIncrementedListener with Listener<ProductCountIncremented> {
     cancel();
   }
 }
-
-class ProductCountChangedMessage {}
-
-class ProductCountIncremented extends ProductCountChangedMessage {}
-
-class ProductCountDecremented extends ProductCountChangedMessage {}

packages/comms/test/listeners/product_count_cubit.dart

@@ -0,0 +1,30 @@
+import 'package:comms/comms.dart';
+
+import '../messages/product_count_changed.dart';
+
+class ProductCountListenerCubit
+    extends ListenerCubit<int, ProductCountChangedMessage> {
+  ProductCountListenerCubit() : super(0);
+
+  @override
+  void onMessage(ProductCountChangedMessage message) {
+    if (message is ProductCountIncremented) {
+      _increment();
+    }
+    if (message is ProductCountDecremented) {
+      _decrement();
+    }
+  }
+
+  @override
+  void onInitialMessage(ProductCountChangedMessage message) =>
+      onMessage(message);
+
+  void _increment() {
+    emit(state + 1);
+  }
+
+  void _decrement() {
+    emit(state - 1);
+  }
+}

packages/comms/test/messages/product_count_changed.dart

@@ -0,0 +1,5 @@
+class ProductCountChangedMessage {}
+
+class ProductCountIncremented extends ProductCountChangedMessage {}
+
+class ProductCountDecremented extends ProductCountChangedMessage {}

packages/comms/test/senders/basket.dart

@@ -1,5 +1,5 @@
 import 'package:comms/comms.dart';
-import '../listeners/product_count.dart';
+import '../messages/product_count_changed.dart';
 
 class Basket with Sender<ProductCountChangedMessage> {
   List<String> products = [];

packages/comms/test/senders/basket_cubit.dart

@@ -0,0 +1,18 @@
+import 'package:bloc/bloc.dart';
+import 'package:comms/comms.dart';
+import '../messages/product_count_changed.dart';
+
+class BasketCubit extends Cubit<List<String>>
+    with Sender<ProductCountChangedMessage> {
+  BasketCubit() : super([]);
+
+  void add(String product) {
+    emit([...state, product]);
+    send(ProductCountIncremented());
+  }
+
+  void removeLast() {
+    emit([...state]..removeLast());
+    send(ProductCountDecremented());
+  }
+}