Is the usage of lombok's @RequiredArgsConstructor good or bad in @QuarkusTest integration tests?

[tippfelher]

I wonder if there is a reason that @requiredargsconstructor should be avoided or not. What is best practice and why?

[rameshreddy-adutla]

Great question! The short answer: avoid @RequiredArgsConstructor in @QuarkusTest classes — it works in some cases but can cause subtle issues.

Why it's problematic

Quarkus uses CDI (Contexts and Dependency Injection) under the hood. CDI has specific rules about how beans are instantiated:

1. CDI requires a no-arg constructor (or a constructor annotated with @Inject). Lombok's @RequiredArgsConstructor generates a constructor with parameters but does NOT add @Inject.

2. In @QuarkusTest, the test class is managed by the CDI container. If CDI can't find a no-arg constructor or an @Inject-annotated constructor, injection may silently fail or throw errors.

3. Field injection with @Inject is the standard pattern in Quarkus tests and is what the documentation recommends.

Best practice

@QuarkusTest
class MyServiceTest {

    @Inject
    MyService myService;  // ✅ Standard Quarkus way

    @InjectMock
    ExternalClient client; // ✅ For mocks

    @Test
    void shouldDoSomething() {
        // test code
    }
}

In production code (non-test)

For application beans, constructor injection IS recommended, but use @Inject explicitly:

@ApplicationScoped
public class MyService {

    private final MyRepository repo;

    @Inject // explicit — no Lombok needed
    public MyService(MyRepository repo) {
        this.repo = repo;
    }
}

Or if you really want Lombok, combine it with @Inject:

@ApplicationScoped
@RequiredArgsConstructor(onConstructor_ = @Inject)
public class MyService {
    private final MyRepository repo;
}

But note that Quarkus (unlike Spring) does not auto-detect single-constructor injection — you always need @Inject.

TL;DR: Use @Inject field injection in test classes. Use explicit @Inject constructor in production beans. Lombok's @RequiredArgsConstructor alone is not enough for CDI.