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flutterflutter-testflutter-provider

How to test provider in view model

I have a view model that a view uses, i want to write a unit test for one of the functions which contains a provider. The function is something like this

Future<String> onSubmit(BuildContext context) async {

PersonProvider personProvider = Provider.of<PersonProvider>(context,listen: false);

String userId = personProvider.user.id;
isLoading = true;
return 'hello';

});}

Is there anyway I can test this, or I have to refactor code

Solution

  • You should refactor your code, if that function is in a ViewModel the problem is that it should not know nothing or as little as possible of the presentation layer. So it should NOT depend on the BuildContext, instead pass in the needed dependencies either directly to the function:

    Future<String> onSubmit(PersonProvider personProvider) async {


String userId = personProvider.user.id;
isLoading = true;
return 'hello';

});}

    Or inject it to the ViewModel constructor, that way you decouple your viewModel from the UI, and from PersonProvider, which can now be passed as a mock for testing.

    If what you are referring to as viewmodel is really just a presenter you could do widget tests and providr a Mock PersonProvider implementation to the widget tree.