Unit testing Scala using mockito - scala

Question

I'm very much new to doing unit testing in Scala using Mockito. I'm getting an error in the thenReturn statement.
it should "read null when readFromPostgresTarget is called with some
random driver" in {
Given("a null query is sent as query")
val query = ""
val pgObject = mock[PersistenceObject]
val postgresPersistenceObject =
mock[PostgressPersistenceServiceTrait]
val mockDF = mock[DataFrame]
When("it is passed to readFromPostgresTarget")
when(postgresPersistenceObject.readFromPostgresTarget(any[String],mock[Spark
Session], pgObject)).thenReturn(mockDF)
assert(postgresPersistenceObject.readFromPostgresTarget(query,
sparkSession, pgObject) === any[DataFrame])
Then("a null value should be returned")
verify(postgresPersistenceObject, times(1))
}
I'm getting the error-
overloaded method value thenReturn with alternatives:
(x$1: Unit,x$2: Unit*)org.mockito.stubbing.OngoingStubbing[Unit] <and>
(x$1: Unit)org.mockito.stubbing.OngoingStubbing[Unit]
cannot be applied to (org.apache.spark.sql.DataFrame)
.thenReturn(mockDF)
I tried making the mockDF in thenReturn(mockDF) to thenReturn(any[DatafRame]), it's not fixing the issue.
I tried passing a SparkSession instead of the mock it isn't working.
I can't figure what mistake I'm doing.

Answer 1

To avoid those problems (related to Scala/Java interop) you should use mockito-scala