Can I make a mock return different values if it is called several times in a recursive calls

Question

I have a recursive function under test f1. f1 calls a database service which I am mocking.

def f1 {
  result = databaseservicecall(arg); //mocking this
  add result to accumulator
  exit recursion if some condition is met else call f1 again.
}

I want that databaseserviecall returns say r1 on 1st call, r2 in the second call and the accumulator should have r1+r2. Alternatively, I am also Ok if I could test that databaseservicecall was called 2 times and that it was passed say arg1 and arg2 as arguments.

Is it possible to do this in mockito? I thought I can use a spy but I don't have a real implementation of databaseservicecall.

Maciej Kowalski · Answer 1 · 2019-05-06T11:15:28.423

0

Take advantage of the thenAnswer feature (doAnswer if you are working with a spy):

Integer invocationCount = Integer.valueOf(0);

when(sut.databaseservicecall(any(Argument.class))).thenAnswer((invocation) ->{
   invocationCount++;

   if(invocationCount == 1) return r1;
   if(invocationCount == 2) return r2;
   if(...)


   return null;
});

More on the feature.

edited May 06 '19 at 11:15

answered May 05 '19 at 11:14

Maciej Kowalski

25,605
12
54
63

how is `invocationCount` getting changed? – Manu Chadha May 05 '19 at 17:06
manually. updated – Maciej Kowalski May 05 '19 at 17:15
The increment is unreachable as you leave the method before the increment. – BeWu May 05 '19 at 20:05
It should be a class instance variable – Maciej Kowalski May 05 '19 at 20:13
1

Still the same result: ```invocationCount++``` can't be reached in the lambda expression. Because you leave the method called in the lambda before because invocationCount is 0. That way only r1 gets returned if you use this code without incrementing before the result is returned. – BeWu May 05 '19 at 21:57
my bad, the increment should be at the beginnin – Maciej Kowalski May 06 '19 at 11:15

score 0 · Answer 2 · answered May 05 '19 at 11:19

0

You can just concatenate then () calls.

when(sut.databaseservicecall(any()))
    .then(r1)
    .then(r2) ;

answered May 05 '19 at 11:19

daniu

14,137
4
32
53

Can I make a mock return different values if it is called several times in a recursive calls

2 Answers2