Integrate mock and testing

[emmanuelbernard]

From Ladislav Thon

2.3. Mock certain ArCDI beans, most likely those that reach out to
external services. (I'm using the word "mock" to mean "test double"
and don't distinguish mocks, stubs, spies etc.) I guess this might
already be possible, as the test class is itself considered a bean and
can define producer methods? (Didn't try.)

[emmanuelbernard]

Probably requires #554 as facility.
Which mock library to push for?

[geoand]

Spring Boot uses Mockito and as far as I have seen, developers enjoy it

[stuartwdouglas]

I don't know if we really need to be mandating a mock library, I think instead we need a general facility to replace beans in tests (our examples/docs should standardise on one lib, but our code should not depend on it).

The real complication here is how we handle the case of different tests needing different Mocks, we could restart Shamrock between tests but that is not great. Instead I think we need two things:

• Something like @Alternative (@TestAlternative maybe), that just allows you to swap out a bean for every test in the test suite
• The ability to replace Normal scoped beans with mocks on a per test basis. This would allow certain functionality to be mocked without needing to restart ArC.

@mkouba what do you think? I can't really think of any other approach that does not involve restarting Shamrock for every test with a different config.

[mkouba]

Hm, I'd rather avoid any client proxies magic and stuff like that. Anything we'll come up with will be brittle. I believe we should restart ArC for each test + allow users to add regular CDI @Alternative mocks. Maybe we could only restart some parts of shamrock?

[Ladicek]

Agree with Stuart that this doesn't necessarily require a mocking library. I can see myself writing mocks manually. (That said, if I were to use a library, it would be Mockito.)

[jordanglassman]

For posterity, the easiest way to use this paradigm alongside a mocking library is to just pass a delegate mock instance from your mock library of choice to the @Alternative.

Here's a jmockit example:

@QuarkusTest
public class MyTest {

   @Inject
    TestContext testContext;

    @Test
    public void onInstalled(@Injectable ClientManager clientManager) throws Exception {
        testContext.setClientManagerDelegate(clientManager);

        given()
                .when()... // do some testing

        new Verifications() {{
            clientManager.createUser(withNotNull());
            times = 1;
        }};
    }......
}

@Mock
public class MockClientManager extends ClientManager {
    @Inject
    TestContext testContext;

    @Override
    public void createUser(@Nonnull final AppClientData appClientData) throws Exception {
        testContext.getClientManagerDelegate().createUser(appClientData);
    }

   ....
}