Why Mockito doesn't handle default Scala parameters properly? - scala

Question

I have a code like
test("mockito test") {
class ToTest {
def run(maybe: Option[Int], q: Option[Int] = None): Int = 42
}
val mockTest = mock[ToTest]
when(mockTest.run(None, None)).thenReturn(98)
mockTest.run(None)
verify(mockTest, times(1)).run(None, None)
}
Which fails with
[info] - mockito test *** FAILED ***
[info] org.mockito.exceptions.verification.junit.ArgumentsAreDifferent: Argument(s) are different! Wanted:
[info] toTest$1.run(None, None);
[info] -> at xxx$$anonfun$3.apply$mcV$sp(xxx.scala:55)
[info] Actual invocation has different arguments:
[info] toTest$1.run(None, null);
Or another scenario
test("mockito test") {
class ToTest {
def run(maybe: Option[Int], q: Int = 5): Int = 42
}
val mockTest = mock[ToTest]
when(mockTest.run(None, 5)).thenReturn(101)
mockTest.run(None)
verify(mockTest, times(1)).run(None, 5)
}
which fails with
[info] - mockito test *** FAILED ***
[info] org.mockito.exceptions.verification.junit.ArgumentsAreDifferent: Argument(s) are different! Wanted:
[info] toTest$1.run(None, 5);
[info] -> at xxx$$anonfun$3.apply$mcV$sp(xxx.scala:55)
[info] Actual invocation has different arguments:
[info] toTest$1.run(None, 0);
I guess it's because there are no default parameters in Java. Is there any workaround for it?
Thank you.

Answer 1

I guess that's because of CGLIB (or Byte Buddy in case of 2.0 beta) generates the code in that case, not Scala compiler, hence the default parameters will be always null.
A workaround could be (at least in some cases) to use spy instead:
val mockTest = spy(classOf[ToTest])
Sorry, no sugar syntax for it in ScalaTest.