I am trying to write a simple test in flutter using MockClient, but I can't seem to get it to work.
Here is the code I am trying to test:
getItemById(int id) async {
final response = await client.get("$_host/item/$id.json");
final decodedJson = json.decode(response.body);
return Item.fromJson(decodedJson);
}
Here is the test code:
test("Test getting item by id", () async {
final newsApi = NewsAPI();
newsApi.client = MockClient((request) async {
final jsonMap = {'id': 123};
Response(json.encode(jsonMap), 200);
});
final item = await newsApi.getItemById(123);
print("Items: ${item.toString()}"); //<-- dosen't print anything.
expect(item.id , 123);
});
When I run the test, it fails with the following message:
NoSuchMethodError: The getter 'bodyBytes' was called on null.
Receiver: null
Tried calling: bodyBytes
I am guessing the issue here is that nothing is returned from the MockClient when I make the call to the getItemById method, but I am not sure why.
I had the same exact issue. You have to return the Response
return Response(json.encode(jsonMap), 200);
Mock expects test function to be EXACTLY as you real function (including OPTIONAL parameters and so on). If both does not match it returns NULL and that is what is happening with your code. Double check to see where your test function is different of original function.
Related
I am using flutter with the cbl package to persist data. Trying to retrieve the entries does not seem to work because the function created is returning at the await statement and not the return statement. This does not seem like the intended result of darts async/await functionality. So I am lost.
task_database.dart
Future<dynamic> getAllTasks() async {
final tasksDb = await Database.openAsync(database); <---------- Returns here
var tasksQuery = const QueryBuilder()
.select(SelectResult.all())
.from(DataSource.database(tasksDb));
final resultSet = await tasksQuery.execute();
late var task;
await for (final result in resultSet.asStream()) {
final map = result.toPlainMap();
final taskDao = TaskDao.fromJson(map);
task = taskDao.task;
// Do something with the task...
print(task);
}
;
return task; <-------------------------------------------- Does not make it here
}
task_cubit.dart
getAllTasks() => {
allTaskMap = TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
What I have tried. I have tried to use Database.openSync instead of Database.openAsync however, the function just returns at the next await statement. I have also tried making getAllTasks asynchronous and awaiting the database as such.
Future<void> getAllTasks() async => {
allTaskMap = await TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
However this has the same issue, when the function from task_database returns prematurely it the returns at the first await function in getAllTasks which is the allTaskMap variable.
Thanks
A function cannot "return prematurely" without a return statement.
The only way the execution is cut short would be an exception being thrown.
I also don't see how you don't get syntax errors, when you don't await the Database.openAsync(database) statement.
So make sure all your awaits are in place. Use the linter to find those that are missing. While you are at it, remove the keyword dynamic from your vocabulary, it will only hurt you if you use it without a need for it. Your return type should be properly typed, then your compiler could tell you, that returning a single task from a function that is clearly supposed to return multiple tasks is not going to work.
Either catch your exceptions and make sure you know there was one, or do not catch them and watch them go all the way through into your debugger.
In addition, following the comment of #jamesdlin, your function definitions are... valid, but probably not doing what you think they are doing.
Future<void> getAllTasks() async => {
allTaskMap = await TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
needs to be
Future<void> getAllTasks() async {
allTaskMap = await TasksAbcDatabase().getAllTasks();
emit(TaskState(tasks: state. Tasks));
}
I am trying to write unit tests for a flutter app and I can't get this one test case to work correctly.
Here is the function returning Future<Either<WeatherData, DataError>>:
#override
Future<Either<WeatherData, DataError>> fetchWeatherByCity({required String city}) async {
try {
var response = await apiService.fetchWeatherByCity(city: city);
if (response.statusCode == 200) {
return Left(WeatherData.fromJson(jsonDecode(response.body)));
} else {
return Right(DataError(title: "Error", description: "Desc", code: 0, url: "NoUrl"));
}
} catch (error) {
AppException exception = error as AppException;
return Right(DataError(
title: exception.title, description: exception.description, code: exception.code, url: exception.url));
}
}
Here is the code where I am trying to write the unit test:
sut = WeatherRepositoryImpl(apiService: mockWeatherApiService);
test(
"get weather by city DataError 1 - Error 404 ",
() async {
when(mockWeatherApiService.fetchWeatherByCity(city: "city"))
.thenAnswer((_) async => Future.value(weatherRepoMockData.badResponse));
final result = await sut.fetchWeatherByCity(city: "city");
verify(mockWeatherApiService.fetchWeatherByCity(city: "city")).called(1);
expect(result, isInstanceOf<DataError>);
verifyNoMoreInteractions(mockWeatherApiService);
},
);
When I run this specific test, I receive this error:
Expected: <Instance of 'DataError'>
Actual: Right<WeatherData, DataError>:<Right(Instance of 'DataError')>
Which: is not an instance of 'DataError'
What I am not getting here? What should I be expecting from the function for the test to pass successfully?
You are directly using the result which is actually a wrapper and has a type of Either<WeatherData, DataError>.
You need to unwrap the value using the fold method on the result and then expect accordingly, So in your code you can do something like this to make it work:
final result = await sut.fetchWeatherByCity(city: "city");
result.fold(
(left) => fail('test failed'),
(right) {
expect(result, isInstanceOf<DataError>);
});
verifyNoMoreInteractions(mockWeatherApiService);
Hope this helps.
You need to either make the expected value a Right(), or extract the right side of the actual value. Doing either of those will match, but as it is, you're comparing a wrapped value with an unwrapped value.
I have this code :
widget.items.sort((a, b) {
await getItemDistance(a, true);
await getItemDistance(b, false);
return (itemADistance)
.compareTo(itemBDistance);
});
I am trying to sort widget.items list based on values returned from getItemDistance. However I get an error with a red squiggly line that says :
The await expression can only be used in an async function
and when I try to add async to the sort method I get another red squiggly line that says :
The argument type 'Future Function(Item, Item)' can't be assigned
to the parameter type 'int Function(Item, Item)'
How do I solve this dilemma guys ? :)
Thanks
List.sort is a synchronous function that expects a synchronous callback; there is no way to use it with an asynchronous callback. I would recommend transforming your List and doing any necessary asynchronous work first and then synchronously sorting the results. Doing so also should avoid calling getItemDistance (which, by virtue of being asynchronous, is likely to be expensive) on the same item multiple times. For example, something like:
final computedDistances = <Item, double>{};
for (final item in widget.items) {
final distance = await getItemDistance(item, ...);
computedDistances[item] = distance;
}
widget.items.sort((a, b) =>
computedDistances[a].compareTo(computedDistances[b])
);
(I don't know what the second argument to getItemDistance represents; if you can't get around that, you would need to build one Map with getItemDistance(..., true) results and one with getItemDistance(..., false) results1.)
As a last resort, you could write your own asynchronous sort function.
Edit #1
This should be a more efficient version since it doesn't wait for each asynchronous operation one-by-one:
final computedDistances = await Future.wait<double>([
for (final item in widget.items) getItemDistance(item, ...),
]);
final computedDistancesMap = <Item, double>{
for (var i = 0; i < widget.items.length; i += 1)
widget.items[i]: computedDistances[i],
};
widget.items.sort((a, b) =>
computedDistancesMap[a].compareTo(computedDistancesMap[b])
);
Edit #2
I've added a List.sortWithAsyncKey extension method to package:dartbag that can do this :
await widget.items.sortWithAsyncKey(
(element) => getItemDistance(element, ...),
);
1 However, if you need to call getItemDistance(..., true) for the first argument and getItemDistance(..., false) for the second argument, that implies that your comparison function probably is not self-consistent.
Whenever you are running async code you should add the async keyword like below. this tells dart you intend to run async code.
Async functions return a Future which tells dart that at some point in the future you are expecting itemADistance or an error.
You will want to return a Future of type int since you are expecting to receive an int itemADistance or an error.
Future<int> widget.items.sort((a, b) async {
await getItemDistance(a, true);
await getItemDistance(b, false);
return (itemADistance)
.compareTo(itemBDistance);
});
I am trying to get Contact using the function getContactsForPhone
getName()async{
number = '123-456-7890'
return await ContactsService.getContactsForPhone(number).then((value) => value.elementAt(0).displayName.toString());
}
but I am getting Future<dynmaic> instead of .displayName which is supposed to be String
You are mixing it up two way's to use Futures:
You can use await keyword to await for the conclusion.
You can use the then method to have a callback when the Future ends.
You need to choose one and stick with it. Using the await is always preferable because it makes the code more readable and avoids some callback hells.
In your case:
Future<String> getName() async {
number = '123-456-7890'
Iterable<Contact> myIterable = await ContactsService.getContactsForPhone(number);
List<Contact> myList = myIterable.toList();
return myList[0].displayName.toString()
}
Which should return the DisplayName you wanted.
Remember to also use the await keyword from the outside, wherever you call this function.
You can read more about Future and Asynchronous code here.
I've been learning flutter for a few weeks and come from an Android background so far I love it and I have also been delighted to find that Flutter was designed with testing in mind from day one. However, I've been having an issue running the following test.
main() => {
test('test get popular repos', () async {
final testOwner = Owner(1010, "testLink");
final testRepo =
Repo(101, testOwner, "testRepo", "description", 'htmlUrl', 500);
final testRepoResponse = RepoResponse(List.from([testRepo]), null);
final uiModel = PopRepo(testRepo.owner.avatarUrl, testRepo.name,
testRepo.description, "Stars: ${testRepo.stargazersCount}");
final searchData = SearchData(List.from([uiModel]), null);
final Repository mockRepository = _mockRepository();
when(mockRepository.getPopularReposForOrg("org"))
.thenAnswer((_) => Future.value(testRepoResponse));
final repoSearchBloc = RepoSearchPageBloc(mockRepository);
await repoSearchBloc.getPopularRepos("org");
await expectLater(repoSearchBloc.resultSubject.stream, emits(searchData));
}),
};
class _mockRepository extends Mock implements Repository {}
My RepoSearchBloc takes data from a Repository and transforms it into the Ui model. Finally it posts that now UI-ready data to the Subject
this is the method under test in the RepoSearchBloc
getPopularRepos(String org) async {
if (org == null || org.isEmpty)
return resultSubject.add(SearchData(List(), null));
RepoResponse response = await _repository.getPopularReposForOrg(org);
if (response.error == null) {
List<Repo> repoList = response.results;
repoList.sort((a, b) => a.stargazersCount.compareTo(b.stargazersCount));
var uiRepoList = repoList
.map((repo) => PopRepo(repo.owner.avatarUrl, repo.name,
repo.description, "Stars: ${repo.stargazersCount}"))
.take(3)
.toList();
resultSubject.add(SearchData(uiRepoList, null));
} else {
ErrorState error = ErrorState(response.error);
resultSubject.add(SearchData(List(), error));
}
When I run the test I keep getting this message no matter what I do it seems with either BehaviorSubject or PublishSubject:
ERROR: Expected: should emit an event that <Instance of 'SearchData'>
Actual: <Instance of 'BehaviorSubject<SearchData>'>
Which: emitted * Instance of 'SearchData'
Any ideas how to get this test to pass?
Ended up figuring this out with the help of a user Nico #Rodsevich of the Flutter Glitter community
anyways using his suggestion to use await for
I came up with the following solution which passed
await for (var emittedResult in repoSearchBloc.resultSubject.stream) {
expect(emittedResult.results[0].repoName, testRepo.name);
return;
}
The RxDart library has some subject tests for reference but my subject being posted to asynchronously did not adhere to their test cases so this solution ended up being just what I needed.
Also #Abion47 's comment also seems to do the job when I move async inside the parameter for expected
expectLater( (await repoSearchBloc.resultSubject.stream.first as SearchData).results[0].repoName, testRepo.name);