How to create a @MockBean with pre-defined answers?

Question

I have a MockBean in my test:

@MockBean(SomeClient.class)
SomeClient client;

I'm starting up a spring-boot test:

@ExtendWith(SpringExtension.class)
@ActiveProfiles("test")
@SpringBootTest(properties = { "spring.jpa.hibernate.ddl-auto=create-drop" })

On spring startup, one of my services is trying to call a method that returns an object, then gets the ID from the returned object:

@Service
public class SomeService {

    public SomeService(final SomeClient someClient) {
        this.someClient = someClient;

        this.clientId = someClient.clientMetadata().getId(); << NullPointerException Here
    }
}

However, I'm getting a NullPointerException because .clientMetadata() returns null.

How do I go about setting up the mock bean so that it returns a Metadata object with the ID populated on it?

Using:

• Java 8
• JUnit 5
• spring-boot-starter-test 2.2.9.RELEASE

PS - I can't use @BeforeEach because it tries to boot the app before it executes the beforeEach method.