Is new App() a good way to test if a spring boot app context loads?

Question

I have just taken over maintenance of an app that has this as its only test: (Yes I know)

@ActiveProfiles("test")
@RunWith(SpringRunner.class)
@RequiredArgsConstructor
@SpringBootTest(classes = App.class)
@MockBean(ElasticSearchIndexService.class)
public class AppStartTest {

    @Test
    public void contextLoads() {
        final var app = new App();
        assertNotNull("the application context should have loaded.", app);
    }
}

Apart from the fact that there is no automated testing in place is this a good way to test if a Spring boot application loads its context? I would have thought that a simple assertTrue(true); in the test would suffice, as the context should be loaded no matter what. Why would I want to create another copy of the application? (I sadly could not find anything related to this during my google searches)

There is also the fact that it has both @RunWith(SpringRunner.class) and @SpringBootTest. The test currently "runs" properly but I would expect that this leads to some unexpected behaviour does it not? I found this SO answer talking about it but it does not go into depth why (or if ever) one should use both annotations.

Lastly I already removed the @RequiredArgsConstructor because I don't really know why it is there in the first place. In my humble opinion it does not really serve a purpose.

I am not certain if this fits SO but I was rather curious as I consider myself somewhat of a beginner Spring developer and maybe the previous dev knew more than me

Answer 1

is this a good way to test if a Spring boot application loads its context?

@M.Deinum already answered this

No it isn't. You should @Autowire your App or rather ApplicationContext and check that.

but for anyone looking for a code example it would look like this:

    @Autowired
    ApplicationContext applicationContext;

    @Test
    public void contextLoads() {
        assertNotNull(applicationContext);
    }

This checks if the Application Context was indeed initialized.

There is also the fact that it has both @RunWith(SpringRunner.class) and @SpringBootTest.

Is a remnant of this test initially using JUnit4, where this was indeed necessary. With JUnit5, which I am using the @RunWith(SpringRunner.class) can be left out.

I still am unsure why the @RequiredArgsConstructor annotation was ever needed but the test runs with and without it so I have removed it.