CODEWITHSUNDEEP
javaunit-testingmockingmockito
AYa
AYa

Reputation: 503

Mockito : Mocking and returning a different type value

Is it possible to return a different type using when-return in mockito.

my function 

m.findDocument(id)

returns a document based on id which I am converting to string for further processing. But, for testing I am fetching the string from a id file. So, effectively I want that string to be returned when the function is called like below :

when(m.findDocument(id)).thenReturn('that_string_from_id_file');

Since, one is of document type and other of String, is there way in mockito I can do the same ?

Thanks

Upvotes: 1

Views: 4042

Answers (2)

GhostCat
GhostCat

Reputation: 140623

Thing is: using a mocking framework doesn't change the Java language.

When the signature of a method is public Foo bar() - then even when calling bar() on a mocked object, that method has to return an instance of Foo. You can't use mocking to silently change the declared return type of a method.

But of course, you can do:

Document mockedDocument = mock(Document.class);
DocumentFinder mockedFinder = mock(DocumentFinder);

when(mockedFinder.findDocument(id)).thenReturn(mockedDocument);
when(mockedDocument.getSomeInfo()).thenReturn("that string");

But please note: you would only mock that Document instance in case you can't use a "real" Document instance. Your goal should be to only use mocking where it is impossible/too-hard without dealing with mocks.

Upvotes: 3

Abhinav Ramakrishnan
Abhinav Ramakrishnan

Reputation: 1090

No. Depending on whether you use when+thenReturn or doReturn/doAnswer, you'll either get a compilation error or a ClassCastException.

What you can do is return a mock document from the method, and then return the test string when the mock is 'converted'.

Upvotes: 0

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