CODEWITHSUNDEEP
flutterstreamflutter-test
Ariel
Ariel

Reputation: 2742

Unit testing stream in flutter with error gives wrong instance

I am trying to ping a server from my code. I am using StreamController<ConnectionState> to check for internet connectivity every 5 (1 in below test) second. The case for the test is passing invalid uri. I want to test that there is an error.

I have tried expectLater(connectionStream, emitsError(ConnectionError)); in the test. However, I am getting the below error.

Error:

Expected: should emit an error that Type:<ConnectionError>
Actual: <Instance of '_ControllerStream<ConnectionState>'>
Which: emitted ! Instance of 'ConnectionError'

File: connection.dart

import 'dart:async';
import 'dart:io';

import 'package:http/http.dart' as http;

class ConnectionController {
  String serverUrl;
  Duration repeatInterval;

  Timer? _timer;

  late final StreamController _controller;

  Stream get stream => _controller.stream;

  ConnectionController({
    this.serverUrl = 'https://google.com',
    this.repeatInterval = const Duration(
      seconds: 5,
    ),
  }) {
    _controller = StreamController<ConnectionState>(
      onListen: () {
        _timer ??= Timer.periodic(repeatInterval, (timer) async {
          try {
            Uri parsedUri = Uri.parse(serverUrl);

            final response = await http.get(parsedUri);

            if (response.statusCode == HttpStatus.ok) {
              _controller.add(ConnectionState(isConnected: true));
            } else {}
          } catch (error, stacktrace) {
            if (error is ArgumentError || error is SocketException) {
              print(error.toString());
              _controller.addError(
                ConnectionError(
                    errorType: ConnectionErrorType.invalidServerUrl,
                    errorDescription: error.toString()),
              );
            }
            print(error);
            print(error.runtimeType);
            print(stacktrace);
          }
        });
      },
      onCancel: () {
        _timer?.cancel();
      },
    );
  }
}

class ConnectionState {
  bool isConnected;
  ConnectionState({
    required this.isConnected,
  });
}

class ConnectionError extends Error {
  ConnectionErrorType errorType;
  String errorDescription;

  ConnectionError({
    required this.errorType,
    required this.errorDescription,
  });
}

enum ConnectionErrorType {
  invalidServerUrl,
}

File: tests\connection_test.dart

import 'package:connection_info/connection.dart';
import 'package:flutter_test/flutter_test.dart';

import 'mocks/connection_error.dart';

void main() {
  group('Connection Controller tests', () {
    test('send invalid server url and get error', () async {
      var connectionError = MockConnectionError();

      final controller = ConnectionController(
        serverUrl: 'http://asdom',
        repeatInterval: Duration(seconds: 1),
      );

      Stream connectionStream = controller.stream;

      expectLater(connectionStream, emitsError(ConnectionError));
    });
  });
}

I want to validate that the stream has received the error. How can I test properly for the error?

Upvotes: 1

Views: 1039

Answers (1)

Loc Tran
Loc Tran

Reputation: 46

I think you should add a matcher in emitsErros, so you can fix like this

expectLater(connectionStream, emitsError(isA<ConnectionError>());

Upvotes: 3

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