How I assert my log message when the log is created by lombok

Question

I have the following code:

@Component
@Slf4j
public class MyClass {

    private OtherClass otherClass;

    @Autowired
    public MyClass(OtherClass otherClass) {
        this.otherClass = otherClass;
    }

    public void start() {
        try {
            otherClass.execute();
        } catch (FeatureException exception) {
            log.warn(exception.getMessage());
        }
    }

I want do test to verify the log message. I dont know how.

Thanks

Answer 1

The SLF4J project recommends using the library SLF4J Test for this use case.

In your case (using Hamcrest and Mockito as well):

public class MyClassTest {

  TestLogger logger = TestLoggerFactory.getTestLogger(MyClass.class);

  @Test
  public void testStart_loggingFailureMessage() {
    OtherClass otherClass = mock(OtherClass.class);
    MyClass myClass = new MyClass(otherClass);

    when(otherClass.execute()).thenThrow(new FeatureException("Some text"));

    myClass.start();

    assertThat(logger.getLoggingEvents(), is(asList(LoggingEvent.warn("Some text"))));
  }

  @After
  public void clearLoggers() {
    TestLoggerFactory.clear();
  }
}