Spring boot 2.0.5.RELEASE - sleuth and mockito

Question

I have tried to sort this out for a week, but no luck at all. The issue is with the unit tests.

This is the class that I am trying to test:

import brave.Span;
import brave.Tracer;

@Service
public class InternetBackEndRestClient {

    @Autowired
    private Tracer tracer;

  public PasswordJwtResponse generatePassworJwt(PasswordJwtRequest passwordJwtRequest, String traceId) throws LogonProxyException {
      log.info("{\"Starting method\": \"generatePassworJwt\", \"input\": {} }", passwordJwtRequest);

    Span newSpan = tracer.nextSpan().name("spanPasswordJwtResponse");
    ...
  }
}

How can I do the unit test? Brave.Tracer is a final class so that I cannot mock it. Is there anyway to set up a context? or mock Tracer?

@RunWith(MockitoJUnitRunner.class)
public class InternetBackEndRestClientTest {

   @InjectMocks
   private InternetBackEndRestClient internetBackEndRestClient; 

   @Mock
   private Tracer tracer; 

   @Test
   public void generatePassworJwt_test() { 
      internetBackEndRestClient.generatePassworJwt(...);
      ....
   }
}

Could anyone help me please?

If you are using Mockito’s JUnit runner how is the application context getting created so that `@Autowired` injection will happen? Can you share a [minimal example](/help/mcve) of what you’re doing please? — Andy Wilkinson, Oct 06 '18 at 10:00

Fany Castro Vizoso · Answer 1 · 2018-10-08T20:02:01.360

Here is the solution that worked for me:

@RunWith(MockitoJUnitRunner.class)
public class InternetBackEndRestClientTest {

    private static final String TRACEID = "12345678901234567890123456789012";

    @InjectMocks
    private InternetBackEndRestClient internetBackEndRestClient;

    @Mock
    private Tracer tracer;
   @Mock
    private Span span;

    @Before
    public void setUp()  {

        MockitoAnnotations.initMocks(this);

        when(tracer.nextSpan()).thenReturn(span);
        when(tracer.nextSpan().name("spanPasswordJwtResponse"))
           .thenReturn(span);
        when(span.start()).thenReturn(span);

        Tracing tracing = Tracing.newBuilder().build();
        doReturn(tracing.tracer().withSpanInScope(span))
             .when(tracer).withSpanInScope(span);
        doNothing().when(span).finish();

        ...
    }
    ...
}

score 3 · Answer 2 · answered Jul 28 '21 at 23:36

You can manually set the span and trace id using TraceContext.newBuilder() in a test and past the Tracer into the class being tested.

Tracer tracer = Tracing.newBuilder().build().tracer();
TraceContext ctx = TraceContext.newBuilder().traceId(10L).spanId(10L).build();
Span span = tracer.toSpan(ctx);
tracer.withSpanInScope(span);

This might be a bit lighter than mocking the Tracer class

score 0 · Answer 3 · answered Oct 07 '18 at 16:55

0

Your example isn't complete so it's hard to identify everything that's not quite right, but one thing is that @MockBean will only work if you're using Spring Boot testing's infrastructure. That means that you need to be using SpringRunner to run the test and you also have to have enabled @MockBean support. The most common way to do that is with @SpringBootTest:

@SpringBootTest
@RunWith(SpringRunner.class)
public class InternetBackEndRestClientTest {
    // …
}

You can read more about @MockBean in the Spring Boot reference documentation.

answered Oct 07 '18 at 16:55

Andy Wilkinson

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Sorry, what do you miss in the example? You can see the class that I am trying to test and the test class as well. I cannot use @MockBean, that's fine. But all I want to do is a unit test with mockito were I need to mock Brave.Trace, so that the instruction "Span newSpan = tracer.nextSpan().name("spanPasswordJwtResponse");" does not fail because the variable "tracer" is null. – Fany Castro Vizoso Oct 07 '18 at 20:32
Your example doesn’t show how you are getting the instance of `InternetBackEndRestClient` that you are testing. For the `@Autowired` on its `tracer` field to work, Spring needs to be creating it. That should happen if you use Spring’s testing infrastructure as described above. You then also need to have the `InternetBackEndRestClientTest` instance that Spring has created injected into your test class. – Andy Wilkinson Oct 08 '18 at 06:08
Thank you. I have updated the example with the part you missed. – Fany Castro Vizoso Oct 08 '18 at 07:26
I have tried to use something like Tracing tracing = Tracing.newBuilder().build(); Tracer tracer = Mockito.mock(Tracer.class); tracer = tracing.tracer(); to create the context with the trace, but "tracer" is still null when I call the real class. – Fany Castro Vizoso Oct 08 '18 at 07:31
Your use of `@InjectMocks` means that Mockito will be creating `InternetBackEndRestClient`. It doesn't know anything about `@Autowired` so the `tracer` field is going to be `null`. If you want the value of the `tracer` field to be set, Spring needs to create the `InternetBackEndRestClient` instance. Using `@SpringBootTest` and `SpringRunner` as I have suggested here will achieve that. – Andy Wilkinson Oct 08 '18 at 12:27

Spring boot 2.0.5.RELEASE - sleuth and mockito

3 Answers3