CODEWITHSUNDEEP
flutterdarttesting
Santiago Curvello
Santiago Curvello

Reputation: 182

Test that a specific exception is thrown in Flutter

I have a test for check an exception:

test('throws an exception if missing data', () async {
  final client = MockClient();
  final _apiService = ApiService(client, 'test/');

  when(
    client.post(
      Uri.parse('test/user/auth_user'),
      headers: {
        'Content-Type': 'application/json',
      },
      body: json.encode({"email": '', "password": ''}),
    ),
  ).thenAnswer(
    (_) async => http.Response(
      '{"status": 400,"data": {"message": "Missing email or password fields"}}',
      400,
    ),
  );

  expect(
    await _apiService.login(email: '', password: ''),
    isA<MissingDataException>(),
  );
});

but is not working, this is the output of the test:

Output for login throws an exception if missing data Instance of 'MissingDataException' package:welivery_scanner/services/api/api.dart 44:11 ApiService.login

This is my exception:

class MissingDataException implements Exception {
  String message;
  MissingDataException(this.message);
}

I tried with

throwsException

and didn't work.

I also tried with

throwsA(TypeMatcher<MissingDataException>())

and also didn't work.

What I can do?

Thanks in advance.

Upvotes: 1

Views: 302

Answers (2)

Santiago Curvello
Santiago Curvello

Reputation: 182

I finally found out that just pulling the await out of the function worked:

expect(
  _apiService.login(email: '', password: ''),
  throwsA(isA<MissingDataException>()),
);

Upvotes: 0

mkobuolys
mkobuolys

Reputation: 5333

Refactor this:

expect(
  await _apiService.login(email: '', password: ''),
  isA<MissingDataException>(),
);

To this:

final fn = () async => await _apiService.login(email: '', password: '');

expect(
  fn,
  throwsA(isA<MissingDataException>())
);

You need to pass a function reference to the expect in order to validate the exception. Now, you are comparing the isA<MissingDataException> with a result from login(), but the exception won't be returned as a result, it should be handled.

Upvotes: 1

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