I am trying to run the code with null safety enabled in the project. I keep getting the following error when I run the test on counter_cubit_test.dart:
import 'package:bloc/bloc.dart';
import 'package:equatable/equatable.dart';
part 'counter_state.dart';
class CounterCubit extends Cubit<CounterState> {
CounterCubit() : super(CounterState(counterValue: 0));
void increment() => emit(
CounterState(counterValue: state.counterValue! + 1, wasIncremented: true));
void decrement() => emit(CounterState(
counterValue: state.counterValue! - 1, wasIncremented: false));
}
part of 'counter_cubit.dart';
class CounterState extends Equatable {
final int? counterValue;
final bool? wasIncremented;
CounterState({required this.counterValue, this.wasIncremented});
@override
List<Object> get props => [this.counterValue!, this.wasIncremented!];
}
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_counter_bloc/cubits/counter_cubit.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Flutter Demo",
theme: ThemeData(
primaryColor: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: BlocProvider<CounterCubit>(
create: (context) => CounterCubit(),
child: MyHomePage(title: "Flutter Demo Home Page"),
),
);
}
}
///Used a stateless widget since state is handled by the Bloc library in this case. I referred the
///following link: https://stackoverflow.com/questions/58864869/flutter-state-management-bloc-stateless-vs-stateful-widget
class MyHomePage extends StatelessWidget {
final String? title;
const MyHomePage({Key? key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title!),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text("You have pushed this button this many times:"),
BlocConsumer<CounterCubit, CounterState>(
///Refactored the if...else block into a function to show the SnackBar Widget
listener: (context, state) => snackBarFunction(state.wasIncremented!, context),
///Refactored the if...else block into a function that returns a Text widget
builder: (context, state) => counterText(state.counterValue!, context)),
SizedBox(height: 24),
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
FloatingActionButton(
onPressed: () => BlocProvider.of<CounterCubit>(context).decrement(),
heroTag: Text("$title"),
tooltip: "Decrement",
child: Icon(Icons.remove),
),
FloatingActionButton(
onPressed: () => BlocProvider.of<CounterCubit>(context).increment(),
heroTag: Text("$title #2"),
tooltip: "Increment",
child: Icon(Icons.add),
),
],
)
],
),
),
);
}
}
///This function is used to show the snack bar widget depending on whether the counter was incremented
///or decremented
void snackBarFunction(bool counterState, context) {
if (counterState == true) {
///Scaffold.of(context).showSnackBar(snackBar) is deprecated
///Using ScaffoldMessenger.of(context).showSnackBar(snackBar) instead
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
content: Text("Incremented!"),
duration: Duration(milliseconds: 300),
));
} else {
ScaffoldMessenger.of(context).showSnackBar(SnackBar(
content: Text("Decremented!"),
duration: Duration(milliseconds: 300),
));
}
}
///This function is used to change the returned Text widget in accordance with the value of the counter
Text counterText(int counterValue, context) {
if (counterValue < 0) {
return Text("BRR, Negative $counterValue",
style: Theme.of(context).textTheme.headline4);
} else if (counterValue % 2 == 0) {
return Text("YAAAY $counterValue",
style: Theme.of(context).textTheme.headline4);
} else if (counterValue == 5) {
return Text("HMM, NUMBER 5", style: Theme.of(context).textTheme.headline4);
} else {
return Text("$counterValue",
style: Theme.of(context).textTheme.headline4);
}
}
import 'package:flutter_counter_bloc/cubits/counter_cubit.dart';
import 'package:test/test.dart';
import 'package:bloc_test/bloc_test.dart';
void main() {
group("CounterCubit", (){
CounterCubit? counterCubit;
setUp((){
counterCubit = CounterCubit();
});
tearDown((){
counterCubit!.close();
});
test("Initial state of CounterCubit is CounterState(counterValue: 0)", () {
expect(counterCubit!.state, CounterState(counterValue: 0));
});
blocTest<CounterCubit, CounterState>(
'the CounterCubit should emit a CounterState(counterValue:1, wasIncremented:true) when the increment function is called',
build: () => counterCubit!,
act: (cubit) => cubit.increment(),
expect: () => <CounterState>[CounterState(counterValue: 1, wasIncremented: true)],
);
blocTest<CounterCubit, CounterState>(
'the CounterCubit should emit a CounterState(counterValue:-1, wasIncremented:false) when the decrement function is called',
build: () => counterCubit!,
act: (cubit) => cubit.decrement(),
expect: () => <CounterState>[CounterState(counterValue: -1, wasIncremented: false)],
);
});
}
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