java - Mockito: mock both return value with callback method -

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• calling callbacks mockito 3 answers

in mockito, want mock method returns value , has invoke callback

for example, here service method:

string fetchstring(callback<string> callback); 

i want return value happen before callback invoked. looked using mockito.doanswer(..) can't seem figure out how make method invoke callback after return statement. example:

when(mockservice.fetchstring(any(callback.class)).thenanswer(     new answer<string>() {         string answer(invocationonmock invocation) {             ((callback<string>) invocation.getarguments()[0]).onresult("callback string");             return "return string";         }     }); 

as can see in example above: callback invoked before value returned. does't test asynchronous callbacks properly. there way make callback method called after value returned?

i know argumentcaptor can used here, there alternative doesn't involve manually calling callback?

something combination of doanswer(..) , thenreturn(..)?

the best way achieve use argumentcaptor, mentioned @talex.

the way used is:

service method:

string fetchstring(callback<string> callback); 

junit test:

argumentcaptor<callback> captor = argumentcaptor.forclass(callback.class); when(mockservice.fetchstring(captor.capture()).thenreturn("return string");  string answer = mockservice.fetchstring(callbacktotest); // callback invoked after service method returned value captor.getvalue().onresult("callback string");  assertequals("return string", answer); verify(callbacktotest).onresult(eq("callback string"));