error migrating to updated flutter_bloc & testing with mockito - flutter

Question

I'm trying to run a test with mockito following an outdated tutorial for a messaging app in flutter. I'm trying to use the most updated versions of everything. The tutorial just implemented flutter bloc, and now I'm getting an error that I don't know how to fix.
This is the test:
import 'package:chat/chat.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:mockito/annotations.dart';
import 'package:mockito/mockito.dart';
import 'package:rethink_chat/states_management/message/message_bloc.dart';
import 'message_bloc_test.mocks.dart';
#GenerateMocks([IMessageService])
void main() {
late MessageBloc sut;
late MockIMessageService messageService; //changed to Mock
late User user;
setUp(() {
messageService = MockIMessageService(); // FakeMessageService();
user = User(
username: 'test',
photoUrl: '',
active: true,
lastseen: DateTime.now(),
);
sut = MessageBloc(messageService);
});
tearDown(() => sut.close());
test('should emit message sent state when message is sent', () {
final message = Message(
from: '123',
to: '456',
contents: 'test message',
timestamp: DateTime.now(),
);
when(messageService.send(message)).thenAnswer((_) async => true);
when(messageService.dispose()).thenAnswer((_) async => <Object?>[]);
sut.add(MessageEvent.onMessageSent(message));
expectLater(sut.stream, emits(MessageState.sent(message)));
});
}
This is the error:
Bad state: add(MessageSent) was called without a registered event handler.
Make sure to register a handler via on<MessageSent>((event, emit) {...})
This is message_event.dart:
part of 'message_bloc.dart';
abstract class MessageEvent extends Equatable {
const MessageEvent();
factory MessageEvent.onSubscribed(User user) => Subscribed(user);
factory MessageEvent.onMessageSent(Message message) => MessageSent(message);
#override
List<Object> get props => [];
}
class Subscribed extends MessageEvent {
final User user;
const Subscribed(this.user);
#override
List<Object> get props => [user];
}
class MessageSent extends MessageEvent {
final Message message;
const MessageSent(this.message);
#override
List<Object> get props => [message];
}
class _MessageReceived extends MessageEvent {
const _MessageReceived(this.message);
final Message message;
#override
List<Object> get props => [message];
}
And message_bloc.dart:
import 'dart:async';
import 'package:bloc/bloc.dart';
import 'package:chat/chat.dart';
import 'package:equatable/equatable.dart';
//import 'package:rethink_chat/states_management/message/message_event.dart';
// import 'package:rethink_chat/states_management/message/message_state.dart';
//import 'package:chat/chat.dart';
part 'message_event.dart';
part 'message_state.dart';
class MessageBloc extends Bloc<MessageEvent, MessageState> {
final IMessageService _messageService;
StreamSubscription?
_subscription; // added a ? but not sure if it's neutral, helpful or harmful
MessageBloc(this._messageService) : super(MessageState.initial());
#override
Stream<MessageState> mapEventToState(MessageEvent event) async* {
if (event is Subscribed) {
await _subscription?.cancel();
_subscription = _messageService
.messages(activeUser: event.user)
.listen((message) => add(_MessageReceived(message)));
}
if (event is _MessageReceived) {
yield MessageState.received(event.message);
}
if (event is MessageSent) {
await _messageService.send(event.message);
yield MessageState.sent(event.message);
}
}
#override
Future<void> close() {
_subscription?.cancel();
_messageService.dispose();
return super.close();
}
}
I saw in another post that flutter bloc at some point removed mapEventToState, but I don't know how to fix this for my situation? I'm so new to this that I have trouble knowing what to fix for this particular code, based on seeing examples of other code.
Please let me know if any other information would be helpful and I'll update this post to include it. I'm a total beginner, so this is hopefully a very simple fix that I'm overlooking. I greatly appreciate any help.
Edit: I also get a similar error for a similar test:
test('should emit messages received from service', () {
final message = Message(
from: '123',
to: '456',
contents: 'test message',
timestamp: DateTime.now(),
);
when(messageService.messages(activeUser: anyNamed('activeUser')))
.thenAnswer((_) => Stream.fromIterable([message]));
when(messageService.dispose()).thenAnswer((_) async => <Object?>[]);
sut.add(MessageEvent.onSubscribed(user));
expectLater(sut.stream, emitsInOrder([MessageReceivedSuccess(message)]));
});
The error is
Bad state: add(Subscribed) was called without a registered event handler.
Make sure to register a handler via on<Subscribed>((event, emit) {...})
I assume the fix should be the same for both, right?
Edit2: so I'm thinking I need to put on<MessageSent>((event, emit) {...}) and on<Subscribed>((event, emit) {...}) somewhere in the code, but where?

Answer 1

Check out the migration guide https://bloclibrary.dev/#/migration
It looks like your code is still version 7.1 or lower. You first need to follow the migration from 7.1 to 7.2. This will show you how to migrate your mapEventToState to the new on<Event> format.