Problems with stubbing spy'ed object in scala - scala

Question

I have a pretty complex test where I decided to go with approach of partial stubbing of tested class. in my test I have something like this:
val srv = new Service()
val srvSpy = spy(srv)
doReturn(now).when(srvSpy).getRunDateInTimeZone(futureChecklist)
doReturn("boo").when(srvSpy).interpolateChecklistName("name", now)
val returnTuple = (createdChlRev, createdChl)
doReturn(returnTuple).when(srvSpy).create(fChlCreatorId,
fChlCreatorEmail,
"username",
true,
templateId,
"boo",
optDueDate)(connection)
val (chlRev, chl) = srv.createFromFutureChecklist(futureChecklist)(connection)
In the code above, the first two stubbed methods working as expected. However, the last one throws an error:
[error] Tuple2 cannot be returned by create$default$8() [error]
create$default$8() should return JsObject [error] *** [error] If
you're unsure why you're getting above error read on. [error] Due
to the nature of the syntax above problem might occur because: [error]
1. This exception might occur in wrongly written multi-threaded tests. [error] Please refer to Mockito FAQ on limitations of
concurrency testing. [error] 2. A spy is stubbed using
when(spy.foo()).then() syntax. It is safer to stub spies - [error]
- with doReturn|Throw() family of methods. More in javadocs for Mockito.spy() method.
I've trying bunch of different approached of stubbing and still getting the same error. At this point I have no idea even where to look.
What am I doing wrong?
Any advice would be helpful.
Thanks

Answer 1

Sorry, it was my own dumb mistake. I was stubbing the spied class, but calling the original one :(
Thanks,