flutter_test expect throws error on Right with List

[adamsmaka]

Hi, I cannot test dartz Right value when type is a list.

  Either<dynamic, List<String>> getStrings() {
    return Right(['Two', 'Three']);
  }

      test(
        'STRINGS',
        () {
          final result = repository.getStrings();
          expect(result, equals(Right(['Two', 'Three'])));
        },
      );

The code above throws error:

ERROR: Expected: Right<dynamic, List>:<Right([Two, Three])>
Actual: Right<dynamic, List>:<Right([Two, Three])>

What am I doing wrong?

[adamsmaka]

Even code like this doesn't work :(
expect(Right(['Two', 'Three']), equals(Right(['Two', 'Three'])));

[mateusfccp]

@adamsmaka Your problem probably has nothing to do with dartz. The same would happen if you was simply comparing the two inner lists, because this is how Dart works regarding lists comparison: it will compare the hashcodes, instead of the list items.

Have a look at #39, the issue is the same.

[spebbe]

As @mateusfccp writes, this is expected behaviour of List equality. If you are able/willing to use IList instead of List, it provides more intuitive default equality semantics, e.g expect(Right(ilist(['Two', 'Three'])), equals(Right(ilist(['Two', 'Three'])))); will succeed.

[adamsmaka]

I did something like that and it works 🤔

if (result.isRight()) {
  final resultList = result.getOrElse(null);
  expect(resultList, equals(myList));
}
expect(result.isRight(), true);

Anyway thanks for answers!

[spebbe]

Yes, the test framework includes special treatment for naked List instances. OK to close?