Testing @ConfigurationProperties with Mockito

Question

I have configuration class:

@ConfigurationProperties(prefix = "myConfig")
public class MyConfig {
    protected String config;
}

My service uses this config class (That gets the value from application.yml):

@Service
public class myService {

    @Inject
    private MyConfig myConfig;

    Public String getInfo (String param) {
        if (isEmpty(param)) { throw new InvalidParameterException; }
        return myConfig.getConfig();
    }
}

I'm trying to test it with Mockito:

@RunWith(MockitoJUnitRunner.class)
public class myTest {

    @InjectMocks
    private MyService myService;

    @Mock
    private MyConfig myConfig;

    @Test
    public void myTest1() {
        myService.getInfo("a");
    }

    @Test
    public void myTest2() {
        assertThrows(InvalidParameterException.class, ()->myService.getInfo(null));
    }
}

myTest fails since the config class is mocked, thus has null values. What is the right way to test configuration class with Mockito?

Edit: I have a number of config classes like the one above that are being used in myService.

Answer 1

You need to create getter which then can be mocked by Mockito.

@ConfigurationProperties(prefix = "myConfig")
public class MyConfig {
    protected String config;

    public String getConfig() {
        return config;
    }
}

.

@RunWith(MockitoJUnitRunner.class)
public class myTest {

    @InjectMocks
    private MyService myService;

    @Mock
    private MyConfig myConfig;

    @Before
    private void initializeConfig() {
        when(myConfig.getConfig()).thenReturn("someValue");
    }

    @Test
    public void myTest1() {
        myService.getInfo("a");
    }
}

But if you don't want to set the value explicitly in test, you should create a Spring integration test which would create the whole context and use the real objects. But this is out of scope of this question.