Upgrade bloc library in hausaufgabenheft_logik package. (#738)

Upgrade the `bloc` package from `^4.0.0` to `^8.1.2`.    
This enables us to make the `hausaufgabenheft_logik` package null-safe
afterwards (#191).

Note: Before there was an abstract "interface" for some blocs in our
code, which I removed because of class types issues (Bloc was `Stream`
before but isn't after upgrading) and also because it's unnecessary.
Thus I also renamed some bloc files which git seems to interpret as
deleting old bloc files and creating new ones.

Closes #729

app/lib/homework/student/src/homework_bottom_action_bar.dart

@@ -166,7 +166,7 @@ class _SortButton extends StatelessWidget {
     final bloc = BlocProvider.of<HomeworkPageBloc>(context);
 
     return StreamBuilder<Success>(
-      stream: bloc.whereType<Success>(),
+      stream: bloc.stream.whereType<Success>(),
       builder: (context, snapshot) {
         final currentSort = snapshot?.data?.open?.sorting;
         return Padding(

app/lib/homework/student/student_homework_page.dart

@@ -88,8 +88,8 @@ class StudentHomeworkBody extends StatelessWidget {
     final bloc = BlocProvider.of<HomeworkPageBloc>(context);
     bloc.add(LoadHomeworks());
     return StreamBuilder<HomeworkPageState>(
-      stream: bloc,
-      initialData: Uninitialized(),
+      stream: bloc.stream,
+      initialData: bloc.state,
       builder: (context, snapshot) {
         final state = snapshot.hasData ? snapshot.data : Uninitialized();
 

app/lib/homework/teacher/src/teacher_homework_bottom_action_bar.dart

@@ -67,7 +67,7 @@ class TeacherSortButton extends StatelessWidget {
     final bloc = BlocProvider.of<TeacherHomeworkPageBloc>(context);
 
     return StreamBuilder<Success>(
-      stream: bloc.whereType<Success>(),
+      stream: bloc.stream.whereType<Success>(),
       builder: (context, snapshot) {
         final currentSort = snapshot?.data?.open?.sorting;
         return Padding(

app/lib/homework/teacher/teacher_homework_page.dart

@@ -90,7 +90,7 @@ class TeacherHomeworkBody extends StatelessWidget {
     final bloc = BlocProvider.of<TeacherHomeworkPageBloc>(context);
     bloc.add(LoadHomeworks());
     return StreamBuilder<TeacherHomeworkPageState>(
-      stream: bloc,
+      stream: bloc.stream,
       initialData: Uninitialized(),
       builder: (context, snapshot) {
         final state = snapshot.hasData ? snapshot.data : Uninitialized();

app/pubspec.lock

@@ -167,10 +167,10 @@ packages:
     dependency: transitive
     description:
       name: bloc
-      sha256: bc0e8756ffa2ba174a6094b2bd4527af8176dc0deb19addb538ad079a2bac75a
+      sha256: "3820f15f502372d979121de1f6b97bfcf1630ebff8fe1d52fb2b0bfa49be5b49"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "8.1.2"
   bloc_base:
     dependency: "direct main"
     description:

app/test/homework/teacher/teacher_homework_page_widget_test.dart

@@ -6,7 +6,6 @@
 //
 // SPDX-License-Identifier: EUPL-1.2
 
-import 'dart:async';
 import 'dart:collection';
 
 import 'package:analytics/analytics.dart';
@@ -34,6 +33,14 @@ class MockTeacherHomeworkPageBloc extends TeacherHomeworkPageBloc {
 
   final receivedEvents = <TeacherHomeworkPageEvent>[];
 
+  MockTeacherHomeworkPageBloc() : super() {
+    on<TeacherHomeworkPageEvent>((event, emit) {
+      if (_queuedStates.isNotEmpty) {
+        emit(_queuedStates.removeFirst());
+      }
+    });
+  }
+
   void emitNewState(TeacherHomeworkPageState state) {
     _queuedStates.add(state);
     add(LoadHomeworks());
@@ -44,17 +51,6 @@ class MockTeacherHomeworkPageBloc extends TeacherHomeworkPageBloc {
     receivedEvents.add(event);
     super.onEvent(event);
   }
-
-  @override
-  Stream<TeacherHomeworkPageState> mapEventToState(
-      TeacherHomeworkPageEvent event) async* {
-    if (_queuedStates.isNotEmpty) {
-      yield _queuedStates.removeFirst();
-    }
-  }
-
-  @override
-  TeacherHomeworkPageState initialState = Uninitialized();
 }
 
 enum HomeworkTab { open, archived }
@@ -303,6 +299,16 @@ void main() {
           hasLength(1),
           reason:
               "The UI should not ask the bloc for new homework when scrolling to the end of the homework list (as all homeworks have already been loaded).");
+
+      // In the teacher homework page bloc which is just a mock right now we use
+      // `await Future.delayed(const Duration(milliseconds: 1200))` to simulate
+      // the loading of homeworks.
+      // Since testWidgets uses fakeAsync interally and Future.delayed uses a
+      // Timer internally we need to pump (advance the fakeAsync time) so that
+      // this test doesn't fail because of this:
+      //  The following assertion was thrown running a test:
+      //  A Timer is still pending even after the widget tree was disposed.
+      tester.pump(Duration(seconds: 2));
     });
 
     testWidgets(
@@ -420,6 +426,9 @@ void main() {
       await tester.pump();
 
       expect(_finders.archivedHomeworkTab.noHomeworkPlaceholder, findsNothing);
+
+      // See test further above for why we need to pump here.
+      tester.pump(Duration(seconds: 2));
     });
   });
 }

lib/abgabe/abgabe_client_lib/pubspec.lock

@@ -75,10 +75,10 @@ packages:
     dependency: transitive
     description:
       name: bloc
-      sha256: bc0e8756ffa2ba174a6094b2bd4527af8176dc0deb19addb538ad079a2bac75a
+      sha256: "3820f15f502372d979121de1f6b97bfcf1630ebff8fe1d52fb2b0bfa49be5b49"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "8.1.2"
   bloc_base:
     dependency: "direct main"
     description:

lib/firebase_hausaufgabenheft_logik/pubspec.lock

@@ -44,10 +44,10 @@ packages:
     dependency: transitive
     description:
       name: bloc
-      sha256: bc0e8756ffa2ba174a6094b2bd4527af8176dc0deb19addb538ad079a2bac75a
+      sha256: "3820f15f502372d979121de1f6b97bfcf1630ebff8fe1d52fb2b0bfa49be5b49"
       url: "https://pub.dev"
     source: hosted
-    version: "4.0.0"
+    version: "8.1.2"
   bloc_base:
     dependency: transitive
     description:

lib/hausaufgabenheft_logik/lib/src/completed_homeworks/completed_homeworks_view_bloc/completed_homeworks_view_bloc.dart

@@ -6,10 +6,69 @@
 //
 // SPDX-License-Identifier: EUPL-1.2
 
+import 'dart:async';
+
+import 'package:bloc/bloc.dart';
+import 'package:bloc_base/bloc_base.dart' as bloc_base;
+import 'package:hausaufgabenheft_logik/src/completed_homeworks/lazy_loading_completed_homeworks_bloc/lazy_loading_completed_homeworks_bloc.dart'
+    as lazy_loading;
+import 'package:hausaufgabenheft_logik/src/completed_homeworks/views/completed_homework_list_view_factory.dart';
+import 'package:rxdart/rxdart.dart';
+
 import 'events.dart';
 import 'states.dart';
 
-abstract class CompletedHomeworksViewBloc
-    implements
-        Stream<CompletedHomeworksViewBlocState>,
-        Sink<CompletedHomeworksViewBlocEvent> {}
+export 'events.dart';
+export 'states.dart';
+
+class CompletedHomeworksViewBloc extends Bloc<CompletedHomeworksViewBlocEvent,
+    CompletedHomeworksViewBlocState> implements bloc_base.BlocBase {
+  final lazy_loading.LazyLoadingCompletedHomeworksBloc
+      _lazyLoadingCompletedHomeworksBloc;
+  final CompletedHomeworkListViewFactory _completedHomeworkListViewFactory;
+  final int nrOfInitialCompletedHomeworksToLoad;
+  StreamSubscription _streamSubscription;
+  Stream<lazy_loading.Success> _lazyLoadingSuccessStates;
+
+  CompletedHomeworksViewBloc(this._lazyLoadingCompletedHomeworksBloc,
+      this._completedHomeworkListViewFactory,
+      {this.nrOfInitialCompletedHomeworksToLoad = 8})
+      : super(Loading()) {
+    _lazyLoadingSuccessStates = _lazyLoadingCompletedHomeworksBloc.stream
+        .whereType<lazy_loading.Success>();
+
+    on<StartTransformingHomeworks>((event, emit) {
+      _lazyLoadingCompletedHomeworksBloc.add(
+          lazy_loading.LoadCompletedHomeworks(
+              nrOfInitialCompletedHomeworksToLoad));
+
+      _streamSubscription = _lazyLoadingSuccessStates.listen((state) {
+        add(_Transform(state));
+      });
+    });
+    on<AdvanceCompletedHomeworks>((event, emit) {
+      _lazyLoadingCompletedHomeworksBloc
+          .add(lazy_loading.AdvanceCompletedHomeworks(event.advanceBy));
+    });
+    on<_Transform>((event, emit) {
+      final success = event.successState;
+      final listView = _completedHomeworkListViewFactory.create(
+          success.homeworks, success.loadedAllHomeworks);
+      emit(Success(listView));
+    });
+  }
+
+  @override
+  void dispose() {
+    _streamSubscription.cancel();
+  }
+}
+
+class _Transform extends CompletedHomeworksViewBlocEvent {
+  final lazy_loading.Success successState;
+
+  _Transform(this.successState);
+
+  @override
+  List<Object> get props => [successState];
+}

lib/hausaufgabenheft_logik/lib/src/completed_homeworks/lazy_loading_completed_homeworks_bloc/lazy_loading_completed_homeworks_bloc.dart

@@ -6,10 +6,62 @@
 //
 // SPDX-License-Identifier: EUPL-1.2
 
+import 'package:bloc/bloc.dart';
+import 'package:bloc_base/bloc_base.dart' as bloc_base;
+
+import '../../data_source/homework_data_source.dart';
+import '../../models/homework_list.dart';
 import 'events.dart';
 import 'states.dart';
 
-abstract class LazyLoadingCompletedHomeworksBloc
-    implements
-        Stream<LazyLoadingCompletedHomeworksBlocState>,
-        Sink<LazyLoadingCompletedHomeworksEvent> {}
+export 'events.dart';
+export 'states.dart';
+
+class LazyLoadingCompletedHomeworksBloc extends Bloc<
+    LazyLoadingCompletedHomeworksEvent,
+    LazyLoadingCompletedHomeworksBlocState> implements bloc_base.BlocBase {
+  final HomeworkDataSource _homeworkRepository;
+  LazyLoadingController _lazyLoadingController;
+
+  LazyLoadingCompletedHomeworksBloc(this._homeworkRepository)
+      : super(Loading()) {
+    on<LoadCompletedHomeworks>(
+      (event, emit) {
+        _lazyLoadingController =
+            _homeworkRepository.getLazyLoadingCompletedHomeworksController(
+                event.numberOfHomeworksToLoad);
+        _lazyLoadingController.results.listen((res) => add(
+              _Yield(Success(
+                HomeworkList(res.homeworks),
+                loadedAllHomeworks: !res.moreHomeworkAvailable,
+              )),
+            ));
+      },
+    );
+    on<AdvanceCompletedHomeworks>(
+      (event, emit) {
+        assert(_lazyLoadingController != null);
+        _lazyLoadingController.advanceBy(event.advanceBy);
+      },
+    );
+    on<_Yield>(
+      (event, emit) => emit(event.payload),
+    );
+  }
+
+  @override
+  void dispose() {}
+}
+
+class _Yield extends LazyLoadingCompletedHomeworksEvent {
+  final dynamic payload;
+  _Yield(this.payload) : assert(payload != null);
+
+  @override
+  List<Object> get props => [payload];
+
+  @override
+  String toString() {
+    return '_Yield(payload: $payload)';
+  }
+}