No support for Quarkus framework?

I am trying out DiffBlue on a small test project using the same software stack as the customer: Quarkus + RestEasy + JDBI.

For both the Repository and the Resource DiffBlue is not able to write a proper test.
All tests have a R013 message.
In all test cases DiffBlue tries to create a new instance of the class under test whereas with Quarkus the test should be annotated with @QuarkusTest and the class-under-test should be injected in the test class optionally mocking any dependent the class-under-test depends on.

Example of simple GreetingResource in Quarkus default application (generated by

public class GreetingResource {

    public String hello() {
        return "Hello from RESTEasy Reactive";

The test generated by DiffBlue succeeds but does not do a test of the Rest Api at all:

class GreetingResourceDiffblueTest {
     * Method under test: {@link GreetingResource#hello()}
    void testHello() {
        // Arrange, Act and Assert
        assertEquals("Hello from RESTEasy Reactive", (new GreetingResource()).hello());

The test should have looked like:

class GreetingResourceTest {
    void testHelloEndpoint() {
             .body(is("Hello from RESTEasy Reactive"));

For a simple UserResource which retrieves some users from a database:

public class UserResource {
    Repository repository;

    public List<User> getUsers() {
        return repository.findUsers();

DiffBlue is not able to create a usable test:

class UserResourceDiffblueTest {
     * Method under test: {@link UserResource#getUsers()}
    @Disabled("TODO: Complete this test")
    void testGetUsers() {
        // TODO: Diffblue Cover was only able to create a partial test for this method:
        //   Reason: No inputs found that don't throw a trivial exception.
        //   Diffblue Cover tried to run the arrange/act section, but the method under
        //   test threw
        //   java.lang.NullPointerException: Cannot invoke "org.acme.Repository.findUsers()" because "this.repository" is null
        //       at org.acme.UserResource.getUsers(
        //   See to resolve this issue.

        // Arrange and Act
        (new UserResource()).getUsers();

And the generated test cases for the Repository class are similar to these.

Am I doing something wrong or is DiffBlue not usable for the Quarkus framework?
Which frameworks/libraries are supported by DiffBlue?

DiffBlue Cover in IntelliJ: 2024.02.02-2023.3
Quarkus: 3.6.8
Java: 21
JDBI: 3.43.0

Hi @Joost

Thanks for trying Diffblue Cover and for getting in touch.
Diffblue Cover does not currently provide support for the Quarkus framework although it is something that we aim to support in the future. Please keep an eye on the Diffblue website and sign up to our newsletter if you’d like to hear about updates.

Diffblue Cover currently supports:

  • Java LTS releases (8, 11, 17, 21)
  • Spring Core 4-6
  • Spring Boot 1-3
  • Writing Java tests for Kotlin code
  • Writing tests for Kafka Producers in a Spring Context

For full details, please see the Diffblue documentation.

Best regards
Peter Sear @ Diffblue