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class StepCounter extends StatefulWidget { | |
int value; | |
final int minValue; | |
final int maxValue; | |
final Function(int) onValueChanged; | |
StepCounter( | |
{@required this.value, | |
@required this.onValueChanged, | |
this.minValue = 0, | |
this.maxValue = 10}) { | |
if (minValue > maxValue) { | |
throw Exception( | |
'Invalid range. Min value ($minValue) must be less than max value ($maxValue)'); | |
} | |
if (value > maxValue || value < minValue) { | |
throw Exception( | |
'Invalid value. The value must be between $minValue and $maxValue'); | |
} | |
} | |
@override | |
_StepCounterState createState() => _StepCounterState(); | |
} | |
class _StepCounterState extends State<StepCounter> { | |
@override | |
Widget build(BuildContext context) { | |
return Row( | |
mainAxisAlignment: MainAxisAlignment.start, | |
children: <Widget>[ | |
StepButton(Icons.remove, () { | |
if (widget.value > widget.minValue) { | |
setState(() { | |
widget.value--; | |
widget.onValueChanged(widget.value); | |
}); | |
} | |
}), | |
Container( | |
width: 60, | |
child: Container( | |
padding: EdgeInsets.all(8), | |
child: Text( | |
widget.value.toString(), | |
style: TextStyle(fontSize: 20), | |
textAlign: TextAlign.center, | |
)), | |
), | |
StepButton(Icons.add, () { | |
if (widget.value < widget.maxValue) { | |
setState(() { | |
widget.value++; | |
widget.onValueChanged(widget.value); | |
}); | |
} | |
}), | |
], | |
); | |
} | |
Widget StepButton(IconData icon, Function f) { | |
return GestureDetector( | |
child: Container( | |
decoration: BoxDecoration(color: Colors.blue), | |
padding: EdgeInsets.all(8), | |
child: Icon( | |
icon, | |
color: Colors.white, | |
)), | |
onTap: () { | |
f(); | |
}, | |
); | |
} | |
} |
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import 'package:first_app/stepper.dart'; | |
import 'package:flutter/material.dart'; | |
import 'package:flutter_test/flutter_test.dart'; | |
void main() { | |
testWidgets('Test step counter', (WidgetTester tester) async { | |
await tester.pumpWidget(MaterialApp( | |
home: StepCounter( | |
value: 1, | |
onValueChanged: (_) {}, | |
), | |
)); | |
// Verify that our counter starts at 0. | |
expect(find.text('1'), findsOneWidget); | |
expect(find.text('0'), findsNothing); | |
// Tap the '+' icon and trigger a frame. | |
await tester.tap(find.byIcon(Icons.add)); | |
await tester.pump(); | |
// Verify that our counter has incremented. | |
expect(find.text('1'), findsNothing); | |
expect(find.text('2'), findsOneWidget); | |
}); | |
testWidgets('Test min value', (WidgetTester tester) async { | |
await tester.pumpWidget(MaterialApp( | |
home: StepCounter( | |
value: 1, | |
minValue: 1, | |
onValueChanged: (_) {}, | |
), | |
)); | |
// Verify that our counter starts at 1. | |
expect(find.text('1'), findsOneWidget); | |
expect(find.text('0'), findsNothing); | |
// Tap the '-' icon and trigger a frame. | |
await tester.tap(find.byIcon(Icons.remove)); | |
await tester.pump(); | |
// Verify that our counter has decremented. | |
expect(find.text('0'), findsNothing); | |
expect(find.text('1'), findsOneWidget); | |
}); | |
testWidgets('Test max value', (WidgetTester tester) async { | |
await tester.pumpWidget(MaterialApp( | |
home: StepCounter( | |
value: 10, | |
maxValue: 10, | |
onValueChanged: (_) {}, | |
), | |
)); | |
// Verify that our counter starts at 10. | |
expect(find.text('10'), findsOneWidget); | |
// Tap the '+' icon and trigger a frame. | |
await tester.tap(find.byIcon(Icons.add)); | |
await tester.pump(); | |
// Verify that our counter has not incremented. | |
expect(find.text('11'), findsNothing); | |
expect(find.text('10'), findsOneWidget); | |
}); | |
} |
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