I'm having a problem with the attached widget tests in flutter. When I run the tests individually, each of them succeeds; however, when I run the entire main() method, the first three tests succeed but the last two fail with the following exception:
Expected: exactly one matching node in the widget tree
Actual: ?:<zero widgets with type "SuccessDialog" (ignoring offstage widgets)>
I understand that the exception means that the widget I'm expecting is not present - what I don't understand is why the test succeeds when run individually but fails after being run after other tests. Is there some instance I need to be "resetting" after each test?
I've tried inserting "final SemanticsHandle handle = tester.ensureSemantics();" at the start of each tests and "handle.dispose();" at the end of each test but got the same results.
EDIT: After some further investigating it seems like the problem may be with how I manage bloc instances using the flutter_bloc package. I have altered my tests to create a new testWidget instance for each test but am still encountering the same problem. Is there anything I may be missing that would cause a bloc instance to persist across testWidget objects?
My new test code looks like this:
main() {
MvnoMockClient.init();
testWidgets(
'Voucher Redemption: Tapping redeem when no values were entered yields 2 field errors',
(WidgetTester tester) async {
Widget testWidget = MediaQuery(
data: MediaQueryData(),
child: MaterialApp(
home: VoucherRedemptionPage(onSuccess: () {}, onFail: () {}),
),
);
await tester.pumpWidget(testWidget);
await tester.tap(find.byType(PrimaryCardButton));
await tester.pump();
expect(find.text("Field is required"), findsNWidgets(2));
});
testWidgets(
'Voucher Redemption: Tapping redeem when only voucher number was entered yields one field error',
(WidgetTester tester) async {
Widget testWidget = MediaQuery(
data: MediaQueryData(),
child: MaterialApp(
home: VoucherRedemptionPage(onSuccess: () {}, onFail: () {}),
),
);
await tester.pumpWidget(testWidget);
await tester.enterText(find.byType(PlainTextField), "0000000000");
await tester.tap(find.byType(PrimaryCardButton));
await tester.pump();
expect(find.text("Field is required"), findsOneWidget);
});
testWidgets(
'Voucher Redemption: Tapping redeem when only mobile number was entered yields one field error',
(WidgetTester tester) async {
Widget testWidget = MediaQuery(
data: MediaQueryData(),
child: MaterialApp(
home: VoucherRedemptionPage(onSuccess: () {}, onFail: () {}),
),
);
await tester.pumpWidget(testWidget);
await tester.enterText(find.byType(MsisdnField), "0815029249");
await tester.tap(find.byType(PrimaryCardButton));
await tester.pump();
expect(find.text("Field is required"), findsOneWidget);
});
testWidgets(
'Voucher Redemption: A successful server response yields a success dialog',
(WidgetTester tester) async {
Widget testWidget = MediaQuery(
data: MediaQueryData(),
child: MaterialApp(
home: VoucherRedemptionPage(onSuccess: () {}, onFail: () {}),
),
);
await tester.pumpWidget(testWidget);
await tester.enterText(find.byType(PlainTextField), "0000000000");
await tester.enterText(find.byType(MsisdnField), "0815029249");
await tester.tap(find.text("REDEEM"));
await tester.pump();
expect(find.byType(SuccessDialog), findsOneWidget);
});
testWidgets(
'Voucher Redemption: An unsuccessful server response yields an error dialog',
(WidgetTester tester) async {
Widget testWidget = MediaQuery(
data: MediaQueryData(),
child: MaterialApp(
home: VoucherRedemptionPage(onSuccess: () {}, onFail: () {}),
),
);
await tester.pumpWidget(testWidget);
gToken = "invalid";
await tester.enterText(find.byType(PlainTextField), "0000000000");
await tester.enterText(find.byType(MsisdnField), "0815029249");
await tester.tap(find.byType(PrimaryCardButton));
await tester.pump();
gToken = "validToken";
expect(find.byType(ErrorDialog), findsOneWidget);
});
}
For additional reference, I have also included the code for the VoucherRedemptionPage and VoucherRedemptionScreen below:
class VoucherRedemptionPage extends StatelessWidget {
final onSuccess;
final onFail;
const VoucherRedemptionPage({Key key, @required this.onSuccess, @required this.onFail})
: super(key: key);
@override
Widget build(BuildContext context) {
var _voucherRedemptionBloc = new VoucherRedemptionBloc();
return Container(
decoration: BoxDecoration(
image: DecorationImage(
image: AssetImage("assets/" + gFlavor + "/primary_background.png"),
fit: BoxFit.cover),
),
child: new Scaffold(
backgroundColor: Colors.transparent,
appBar: new AppBar(
title: new Text(gDictionary.find("Redeem Voucher")),
),
body: new VoucherRedemptionScreen(
voucherRedemptionBloc: _voucherRedemptionBloc,
onSuccess: this.onSuccess,
onFail: this.onFail,
),
),
);
}
}
class VoucherRedemptionScreen extends StatefulWidget {
const VoucherRedemptionScreen({
Key key,
@required VoucherRedemptionBloc voucherRedemptionBloc,
@required this.onSuccess,
@required this.onFail,
}) : _voucherRedemptionBloc = voucherRedemptionBloc,
super(key: key);
final VoucherRedemptionBloc _voucherRedemptionBloc;
final onSuccess;
final onFail;
@override
VoucherRedemptionScreenState createState() {
return new VoucherRedemptionScreenState(
_voucherRedemptionBloc, onSuccess, onFail);
}
}
class VoucherRedemptionScreenState extends State<VoucherRedemptionScreen> {
final VoucherRedemptionBloc _voucherRedemptionBloc;
final onSuccess;
final onFail;
TextEditingController _msisdnController = TextEditingController();
TextEditingController _voucherPinController = TextEditingController();
GlobalKey<FormState> _formKey = GlobalKey<FormState>();
VoucherRedemptionScreenState(
this._voucherRedemptionBloc, this.onSuccess, this.onFail);
@override
void initState() {
super.initState();
}
@override
void dispose() {
super.dispose();
}
@override
Widget build(BuildContext context) {
return BlocBuilder<VoucherRedemptionEvent, VoucherRedemptionState>(
bloc: _voucherRedemptionBloc,
builder: (
BuildContext context,
VoucherRedemptionState currentState,
) {
if (currentState is VoucherRedemptionInitial) {
_voucherPinController.text = currentState.scannedNumber;
return _buildFormCard();
}
if (currentState is VoucherRedemptionLoading) {
return Center(
child: CircularProgressIndicator(),
);
}
if (currentState is VoucherRedemptionSuccess) {
return SuccessDialog(
title: gDictionary.find("Voucher Redeemed Successfully"),
description: currentState.successMessage,
closeText: gDictionary.find("OK"),
closeAction: () {
this.onSuccess();
_voucherRedemptionBloc.dispatch(ResetVoucherRedemptionState());
},
);
}
if (currentState is VoucherRedemptionError) {
return ErrorDialog(
errorCode: currentState.errorCode,
errorMessage: currentState.errorMessage,
closeText: gDictionary.find("OK"),
closeAction: () {
this.onFail();
_voucherRedemptionBloc.dispatch(ResetVoucherRedemptionState());
},
);
}
},
);
}
Widget _buildFormCard() {
return Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.only(
topLeft: Radius.circular(8), topRight: Radius.circular(8))),
padding: EdgeInsets.fromLTRB(12, 12, 12, 0),
width: double.infinity,
height: double.infinity,
child: _buildCardContent(),
);
}
Widget _buildCardContent() {
return SingleChildScrollView(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
gDictionary.find("Transaction Amount"),
style: TextStyle(
fontSize: 14,
color: Theme.of(context).primaryColorDark,
fontWeight: FontWeight.bold),
),
Container(height: 16),
Form(
key: _formKey,
child: _buildFormContent(),
),
],
),
);
}
Column _buildFormContent() {
return Column(
children: <Widget>[
PlainTextField(
controller: _voucherPinController,
label: gDictionary.find("Voucher Number"),
required: true,
),
Container(height: 16),
MsisdnField(
controller: _msisdnController,
label: gDictionary.find("Mobile Number"),
required: true,
),
Divider(),
Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
SecondaryCardButton(
text: gDictionary.find("SCAN VOUCHER"),
onPressed: () {
_voucherRedemptionBloc.dispatch(
ScanBarcode(),
);
},
),
Container(
width: 8.0,
),
PrimaryCardButton(
text: gDictionary.find("REDEEM"),
onPressed: () {
if (_formKey.currentState.validate()) {
_voucherRedemptionBloc.dispatch(
RedeemVoucher(
_voucherPinController.text,
_msisdnController.text,
),
);
}
},
),
],
)
],
);
}
}
Found the problem. I was using the singleton pattern when creating an instance of the bloc - this caused states to persist across different widget objects. Very unlikely that anyone will encounter the same problem that I did but below is the code that I changed to mitigate the problem
Old problematic code:
class VoucherRedemptionBloc
extends Bloc<VoucherRedemptionEvent, VoucherRedemptionState> {
static final VoucherRedemptionBloc _voucherRedemptionBlocSingleton =
new VoucherRedemptionBloc._internal();
factory VoucherRedemptionBloc() {
return _voucherRedemptionBlocSingleton;
}
VoucherRedemptionBloc._internal();
//...
}
Updated working code:
class VoucherRedemptionBloc
extends Bloc<VoucherRedemptionEvent, VoucherRedemptionState> {
VoucherRedemptionBloc();
//...
}