Cannot mock annotated field using Mockito

Question

Following is the subject under test RestClient.java

package com.demo.mockito;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.Validate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import com.demo.sample1.RestClient;
import com.demo.sample2.AboutApi;
import com.demo.sample3.ServiceInfo;
import com.demo.sample4.FeatureRepo;

@Component
@Slf4j
public class RestClient {

    @Value("${test.api.baseURL:http://localhost:80}")
    private String baseURL;

    private static String ACTIVE = "ACTIVE";

    @Autowired(required = false)
    private TokenService tokenService;

    private FeatureRepo featureRepo;

    RestClient(FeatureRepo featureRepo) {
        this.FeatureRepo = featureRepo;
    }

    public boolean isEnabled() {
        AboutApi aboutApi = new AboutApi(getApiClient());
        ServiceInfo serviceInfo = aboutApi.getMultiSiteServiceInfo();
        Validate.notNull(serviceInfo);
        return ACTIVE.equals(serviceInfo.getStatus());
    }

    private ApiClient getApiClient() {
        ApiClient apiClient = new ApiClient();
        apiClient.setBasePath(baseURL);
        return apiClient;
    }
}

And this one is the test RestClientTest.java

package com.demo.mockito;

import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.when;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.powermock.modules.junit4.PowerMockRunner;
import com.demo.sample1.RestClient;
import com.demo.sample2.AboutApi;
import com.demo.sample3.ServiceInfo;
import com.demo.sample4.FeatureRepo;


@RunWith(PowerMockRunner.class)
public class RestClientTest {
    @InjectMocks private RestClient restClient;

    @Mock private AboutApi aboutApiClient;

    @Mock ServiceInfo serviceInfo;

    @Mock FeatureRepo featureRepo;

    @Before
    public void init() throws ApiException {
        when(aboutApiClient.getServiceInfo()).thenReturn(serviceInfo);
        when(serviceInfo.getStatus()).thenReturn("ACTIVE");
    }

    @Test
    public void testIsEnabled() throws ApiException {
        boolean status = restClient.isEnabled();
        assertTrue(status);
    }
}

When I run the test, ideally as it reaches the 2nd line of RestClient.java's isEnabled method, the output should be mocked as stated in 1st line of @Before but it tries to call the real method leading to IllegalArgumentException.

Can someone please tell me how can I properly mock that call without doing any changes in the file RestClient.java ?

Answer 1

Edit: Updated

I have issue in the line AboutApi aboutApi = new AboutApi(getApiClient()). Here it is calling a new instance instead of using the one which I mocked. I want to know how can I insert my mocked instance of AboutApi without touching RestClient.java

In that case you have to take a look at PowerMockito's whenNew functionality.

You will have to add the @PrepareForTest annotation so that it includes the class that needs to be modified, in your case RestClient.

@RunWith(PowerMockRunner.class)
@PrepareForTest(RestClient.class)

Not sure whether that is a typo in your question, but the method you need to define behaviour for should be getMultiSiteServiceInfo instead of getServiceInfo.

@Test
public void testIsEnabled() throws Exception {

    Mockito.when(aboutApiClient.getMultiSiteServiceInfo()).thenReturn(serviceInfo);
    Mockito.when(serviceInfo.getStatus()).thenReturn("ACTIVE");

    PowerMockito.whenNew(AboutApi.class)
                .withAnyArguments()
                .thenReturn(aboutApiClient);

    boolean status = restClient.isEnabled();
    Assert.assertTrue(status);
}

You can replace withAnyArguments() with withArguments(Mockito.any(ApiClient.class)) if you want to be more specific.

Note however that the fields tokenService and baseUrl in your RestClient class will be null.