java assert log in unit testing

junit assert log in unit testing

public class FooService {

    private static final Logger LOGGER = LoggerFactory.getLogger(FooService.class);

    public void sayHello() {
        LOGGER.warn("Congratulations, you are pregnant!");
    }

}

junit assert on a message in a logger test

public class FooServiceTest {

    private LogCaptor logCaptor = LogCaptor.forClass(FooService.class);

    @Test
    public void logInfoAndWarnMessages() {
        FooService fooService = new FooService();
        fooService.sayHello();

        assertThat(logCaptor.getWarnLogs())
            .contains("Congratulations, you are pregnant!");
    }
}