No bean found for definition [SpyDefinition... when using @SpyBean

I have an application that listens for Kafka messages using @KafkaListener inside of a @Component. Now I'd like to make an integration test with a Kafka test container (which spins up Kafka in the background). In my test I want to verify that the listener method was called and finished, however when I use @SpyBean in my test I get:

No bean found for definition [SpyDefinition@7a939c9e name = '', typeToSpy = com.demo.kafka.MessageListener, reset = AFTER]

I'm using Kotling, important classes:

Class to test

@Componentclass MessageListener(private val someRepository: SomeRepository){    @KafkaListener    fun listen(records: List<ConsumerRecord<String, String>>) {         // do something with someRepository    }}

Base test class

@ExtendWith(SpringExtension::class)@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.MOCK)@TestInstance(TestInstance.Lifecycle.PER_CLASS)class KafkaContainerTests {    // some functionality to spin up kafka testcontainer}

Test class

class MessageListenerTest @Autowired constructor(        private val someRepository: SomeRepository) : KafkaContainerTests() {    @SpyBean    private lateinit var messageListenerSpy: MessageListener    private var messageListenerLatch = CountDownLatch(1)    @BeforeAll    fun setupLatch() {        logger.debug("setting up latch")        doAnswer {            it.callRealMethod()            messageListenerLatch.count        }.whenever(messageListenerSpy).listen(any())    }    @Test    fun testListener(){        sendKafkaMessage(someValidKafkaMessage)        // assert that the listen method is being called & finished        assertTrue(messageListenerLatch.await(20, TimeUnit.SECONDS))        // and assert someRepository is called    }}

The reason I am confused is that when I add the MessageListener to the @Autowired constructor of the MessageListenerTest it does get injected successfully.

Why is the test unable to find the bean when using @SpyBean?