How can I test / mock Hive (Flutter) open box logic in repo? - unit-testing

Question

Sorry if this seems a dumb question. I'm learning clean architecture as dictated by Rob Martin, and I've having a tiny bit of trouble writing one of my tests.
I wrote a couple functions in a Hive repo. Here's the code
import 'package:hive/hive.dart';
import 'package:movie_browser/features/SearchMovie/domain/entities/movie_detailed_entity.dart';
abstract class HiveMovieSearchRepoAbstract {
Future<void> cacheMovieDetails(MovieDetailed movie);
Future<MovieDetailed> getCachedMovieDetails(String id);
}
// const vars to prevent misspellings
const String MOVIEDETAILSBOX = "MovieDetailedBox";
const String SEARCHBOX = "SearchBox";
class HiveMovieSearchRepo implements HiveMovieSearchRepoAbstract {
Box movieDetailsBox = Hive.box(MOVIEDETAILSBOX) ?? null;
// TODO implement searchbox
// final searchBox = Hive.box(SEARCHBOX);
Future<void> cacheMovieDetails(MovieDetailed movie) async {
/// expects a MovieDetailed to cache. Will cache that movie
movieDetailsBox ?? await _openBox(movieDetailsBox, MOVIEDETAILSBOX);
movieDetailsBox.put('${movie.id}', movie);
}
Future<MovieDetailed> getCachedMovieDetails(String id) async {
/// expects a string id as input
/// returns the MovieDetailed if cached previously
/// returns null otherwise
movieDetailsBox ?? await _openBox(movieDetailsBox, MOVIEDETAILSBOX);
return await movieDetailsBox.get('$id');
}
_openBox(Box box, String type) async {
await Hive.openBox(type);
return Hive.box(type);
}
}
I can't think of how to test this? I want two cases, one where the box is already opened, and one case where it isn't.
Specifically, it's these lines I want to test
movieDetailsBox ?? await _openBox(movieDetailsBox, MOVIEDETAILSBOX);
_openBox(Box box, String type) async {
await Hive.openBox(type);
return Hive.box(type);
}
I thought about mocking the Box object then doing something like....
when(mockHiveMovieSearchRepo.getCachedMovieDetails(some_id)).thenAnswer((_) async => object)
but wouldn't that bypass the code I want tested and always show as positive?
Thanks so much for the help

Answer 1

i don't know if i fully understand your question but you can try something like this
abstract class HiveMovieSearchRepoAbstract {
Future<void> cacheMovieDetails(MovieDetailed movie);
Future<MovieDetailed> getCachedMovieDetails(String id);
}
// const vars to prevent misspellings
const String MOVIEDETAILSBOX = "MovieDetailedBox";
const String SEARCHBOX = "SearchBox";
class HiveMovieSearchRepo implements HiveMovieSearchRepoAbstract {
final HiveInterface hive;
HiveMovieSearchRepo({#required this.hive});
#override
Future<void> cacheMovieDetails(MovieDetailed cacheMovieDetails) async {
/// expects a MovieDetailed to cache. Will cache that movie
try {
final moviedetailbox = await _openBox(MOVIEDETAILSBOX);
moviedetailbox.put('${movie.id}', movie);
} catch (e) {
throw CacheException();
}
}
Future<MovieDetailed> getCachedMovieDetails(String id) async {
/// expects a string id as input
/// returns the MovieDetailed if cached previously
/// returns null otherwise
try {
final moviedetailbox = await _openBox(MOVIEDETAILSBOX);
if (moviedetailbox.containsKey(boxkeyname)) {
return await movieDetailsBox.get('$id');
}
return null;
} catch (e) {
return CacheException();
}
}
Future<Box> _openBox(String type) async {
try {
final box = await hive.openBox(type);
return box;
} catch (e) {
throw CacheException();
}
}
}
And to test it you can do something like this
class MockHiveInterface extends Mock implements HiveInterface {}
class MockHiveBox extends Mock implements Box {}
void main() {
MockHiveInterface mockHiveInterface;
MockHiveBox mockHiveBox;
HiveMovieSearchRepo hiveMovieSearchRepo;
setUp(() {
mockHiveInterface = MockHiveInterface();
mockHiveBox = MockHiveBox();
hiveMovieSearchRepo = HiveMovieSearchRepo(hive: mockHiveInterface);
});
group('cacheMoviedetails', () {
test(
'should cache the movie details',
() async{
//arrange
when(mockHiveInterface.openBox(any)).thenAnswer((_) async => mockHiveBox);
//act
await hiveMovieSearchRepo.cacheMovieDetails(tcacheMovieDetails);
//assert
verify(mockHiveBox.put('${movie.id}', tmovie));
verify(mockHiveInterface.openBox("MovieDetailedBox"));
});
});
group('getLocalCitiesAndCountriesAtPage', () {
test('should when', () async {
//arrange
when(mockHiveInterface.openBox(any))
.thenAnswer((realInvocation) async => mockHiveBox);
when(mockHiveBox.get('$id'))
.thenAnswer((realInvocation) async => tmoviedetails);
//act
final result =
await hiveMovieSearchRepo.getCachedMovieDetails(tId);
//assert
verify(mockHiveInterface.openBox(any));
verify(mockHiveBox.get('page${tpage.toString()}'));
expect(result, tmoviedetails);
});
});
}
You should add some tests also for the CacheExeption().
Hope this help you.

Answer 2

So, I wrote this post 9 months. Stackoverflow just sent me a notification saying it's a popular question, so I'll answer it for anyone else wondering the same thing
Easy way to make this testable is change Box to an arg passed into the class, like so
abstract class ClassName {
final Box movieDetailsBox;
final Box searchBox;
ClassName({
this.moveDetailsBox,
this.searchBox,
});
}
this makes the boxes mockable and testable

Answer 3

You should mock the hive interface and box;