Kotlin, JUnit , Mockito: @MockBean does not inject a mocked bean

[yacinelakel]

Expected Behavior

Injected beans in a test class using @MicronautTest and @MockBean should inject a mock of the bean.

Actual Behaviour

The injected bean is not a mock, but instead the actual instance of the bean.

Steps To Reproduce

1. Create a new Micronaut Application (v 4.9.3)

mn create-app --build=gradle_kotlin --jdk=21 --lang=kotlin --test=junit --features=http-client,mockito com.example.kotlin-junit

2. Add a simple singleton class

@Singleton
open class EchoServiceImpl {
    open fun echo(message: String): String {
        return message
    }
}

3. Update the KotlinJunitTest to create a mock using @MockBean, and inject it into the test class

@MicronautTest
open class KotlinJunitTest {

    @Inject
    lateinit var application: EmbeddedApplication<*>

    @Inject
    lateinit var echoService: EchoServiceImpl

    @Test
    fun testItWorks() {
        Assertions.assertTrue(application.isRunning)
    }

    @Test
    fun echoServiceIsMocked() {
        Assertions.assertTrue(Mockito.mockingDetails(echoService).isMock)
    }

    @MockBean(EchoServiceImpl::class)
    open fun echoService(): EchoServiceImpl {
        return Mockito.mock(EchoServiceImpl::class.java)
    }
}

Environment Information

No response

Example Application

https://github.com/yacinelakel/micronaut-kotlin-junit-mockbean-issue

Version

4.9.3