Argument passed to when() is not a mock! Example of correct stubbing: doThrow(new RuntimeException()).when(mock).someMethod(); - kotlin

Question

When using Mockito in JUnit4, I encounter the error in the title.
My code is shown below
package cn.patest.judgerAutoscalerKotlin
import org.junit.Test
import org.mockito.*
import java.lang.RuntimeException
class CalculateScaleToTest {
#Mock
private lateinit var test: cn.patest.judgerAutoscalerKotlin.Test
private fun mockTest() {
test = cn.patest.judgerAutoscalerKotlin.Test()
Mockito.doAnswer { 1 }.`when`(test).test()
}
#Test
fun z() {
mockTest()
}
}
package cn.patest.judgerAutoscalerKotlin
class Test() {
fun test(): Int {
return 1
}
}
Error details are shown below:
org.mockito.exceptions.misusing.NotAMockException:
Argument passed to when() is not a mock!
Example of correct stubbing:
doThrow(new RuntimeException()).when(mock).someMethod();
at cn.patest.judgerAutoscalerKotlin.CalculateScaleToTest.mockTest(CalculateScaleToTest.kt:53)
at cn.patest.judgerAutoscalerKotlin.CalculateScaleToTest.z(CalculateScaleToTest.kt:61)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
I searched with google and found some similar issues but they have different situations from mine.

Answer 1

With:
test = cn.patest.judgerAutoscalerKotlin.Test()
you create a real object, not a mocked one.
Remove the above line and add:
#Before
fun before() {
MockitoAnnotations.initMocks( this )
}
Reference:
Mock
MockitoAnnotations
MockitoAnnotations.initMocks(this) method has to be called to initialize annotated fields.
Note also that mocking the class under test in a real environment doesn't make any sense (in contrast to a MCVE like here).