Unit test LazyLogging using Mockito - scala

Question

I am having a class which extends LazyLogging trait
class TaskProcessor()
extends Processor
with LazyLogging {
def a1() = {
logger.info("Test logging")
}
}
Now, I want to test whether my logging works. So I followed this example Unit test logger messages using specs2 + scalalogging and wrote my test as follows
"TaskProcessor" should "test logging" in {
val mockLogger = mock[Logger]
val testable = new TaskProcessor {
override val logger: Logger = mockLogger
}
verify(mockLogger).info("Test logging")
}
I get the following error
Error:(32, 20) overriding lazy value logger in trait LazyLogging of type com.typesafe.scalalogging.Logger;
value logger must be declared lazy to override a concrete lazy value
override val logger: Logger = mockLogger
To resolve this, I modify statement
override val logger: Logger = mockLogger
to
override lazy val logger: Logger = mockLogger
I get the following error
Cannot mock/spy class com.typesafe.scalalogging.Logger
Mockito cannot mock/spy following:
- final classes
- anonymous classes
- primitive types
org.mockito.exceptions.base.MockitoException:
Cannot mock/spy class com.typesafe.scalalogging.Logger
Mockito cannot mock/spy following:
- final classes
- anonymous classes
- primitive types
at org.scalatest.mockito.MockitoSugar.mock(MockitoSugar.scala:73)
at org.scalatest.mockito.MockitoSugar.mock$(MockitoSugar.scala:72)
My dependecies are as follows
"org.scalatest" %% "scalatest" % "3.0.5" % "test",
"org.mockito" % "mockito-all" % "1.10.19" % Test,
"com.typesafe.scala-logging" %% "scala-logging" % "3.9.2",
Can anyone please guide me as to how I can mock the logger and do the testing.

Answer 1

The problem is that com.typesafe.scalalogging.Logger class cannot be mocked because it's final, but we still can mock underlying org.slf4j.Logger.
import org.scalatest.mockito.MockitoSugar
import org.slf4j.{Logger => UnderlyingLogger}
import com.typesafe.scalalogging.Logger
import org.scalatest.{Matchers, WordSpec, FlatSpec}
import org.mockito.Mockito._
class TaskProcessorSpec extends FlatSpec with Matchers with MockitoSugar {
"TaskProcessor" should "test logging" in {
val mockLogger = mock[UnderlyingLogger]
when(mockLogger.isInfoEnabled).thenReturn(true)
val testable = new TaskProcessor {
override lazy val logger = Logger(mockLogger)
}
testable.a1()
verify(mockLogger).info("Test logging")
}
}