How are doReturn and toReturn different in Mockito?

Question

Is there any difference between these two lines of code?

Option 1:

doReturn(masterQuery).when(tldSpy).makeMyInsightAPIQuery(anyString());

Option 2:

stub(tldSpy.makeMyInsightAPIQuery(anyString())).toReturn(masterQuery);

Someone else asked a similar question (Mockito - difference between doReturn() and when()) but I'm asking about toReturn() which was not addressed in that question.

score 1 · Accepted Answer · edited May 23 '17 at 12:29

stub(T).toReturn(...) is just a deprecated syntax replaced by when(T).thenReturn(...). Same rules and guidelines apply as in the question you linked:

when().thenReturn() and stub().toReturn() can do return type checking
doAnswer().when() is the only way to stub void methods
doReturn().when() avoids calling the real method in spies and already-stubbed objects

Otherwise, they have exactly the same behavior and the same consequences, and can be used interchangeably.

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