CODEWITHSUNDEEP
unit-testingmockingdartmockitoangular-dart
Fallenreaper
Fallenreaper

Reputation: 10704

Is there a way to pass in complex arguments into Mocked Dart Services using Mockito?

I was looking at the documentation at: https://pub.dartlang.org/packages/mockito and was trying to understand it more. It seems that in the examples, the function stubs were accepting strings, but was kind of confused as to how I was going to implement my Mocked Services.

I was curious how I would do it. The services I have is pretty simple and straight forward.

class Group{}
class GroupService {}
class MockGroupService extends Mock implements GroupService {}
final mockProviders = [new Provider(MockGroupService, useExisting: GroupService];

So you can see I am using Angular dart.

I was creating a sample group in my Test file.

group("service tests", (){
  MockGroupService _mock;
  testBed.addProviders([mockProviders]);

  setUp(() async {
    fixture = await testBed.create();
    _mock = new MockGroupService();

    //This is where I was going to create some stubbs for the methods
    when(_mock.add()).thenReturn((){
      return null; //return the object.
    });

    //create additional when statements for edit, delete, etc.
  });
});

So what i was thinking is that there would be an argument passed into add (or 2).... how would I properly code that in the when statement, and how do those 2 arguments reflect in the then statement?

Essentially, I was wanting to do a test with a complex class.. and pass it into add. Then it would just process it accordingly and return it.

Do i pass into the arguments something akin to: (using pseudocode)

when(_mock.add(argThat(hasType(Group)))).thenReturn((Group arg)=> arg);

or something similar? hasType isnt function, so im not 100% sure how to approach this design. Ideally, Im trying create the Group in the test, and then pass it into the add function accordingly. It just seems that the examples were showing Strings.

Upvotes: 3

Views: 2391

Answers (1)

Ted Sander
Ted Sander

Reputation: 1899

Yes mockito allows objects to be passed you can see examples in the test.

It is a bit hard to follow but you can see here that it uses deep equality to check if arguments are equal if no matchers are specified.

The second part of your question is a bit more complex. If you want to use the values that were passed into your mock as part of your response then you need to use thenAnswer. It provides you with an Invocation of what was just called. From that object you can get and return any arguments that were used in the method call.

So for your add example if you know what is being passing in and have complete access to it I would write:

Group a = new Group();
when(_mock.add(a)).thenReturn(a);

If the Group object is being created by something else I would write:

when(_mock.add(argThat(new isInstanceOf<Group>()))
  .thenAnswer((invocation)=>invocation.positionalArguments[0]);

Or if you don't really care about checking for the type. Depending on what checks you are using for your test the type might already be checked for you.

when(_mock.add(any)).thenAnswer(
  (invocation)=>invocation.positionalArguments[0]);

Or if you are using Dart 2.0:

when(_mock.add(typed(any))).thenAnswer(
  (invocation)=>invocation.positionalArguments[0]);

Upvotes: 2

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