如何模拟正在测试的类的某些对象？

Question

I've the below class that I want to test:

@Component
public class ToBeTested {
 @Autowired
 private HelperA helperA;

 @Autowired
 private HelperB helperB;

 ... //10 other such helpers
}

I want to mock ONLY HelperA class. How do I do this in jUnit? I do not want to mock the other helper classes. Nor do I want to write @Spy & @Resource for all of the helpers and use @InjectMocks in the test case.

Is there a way for me to inject only the mock of HelperA into the ToBeTested class in the test case?

Answer 1

To summarize, you want to use a mocked HelperA but an @Autowired HelperB ?

I wrote an article on this that can help: http://www.sleepeasysoftware.com/how-to-mock-out-a-deeply-nested-class-in-spring-without-going-insane/

To summarize, put this at the top of your test class:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = ASubclassOfYourRealConfig.class)

Then you create ASubclassOfYourRealConfig to look like this:

public class ASubclassOfYourRealConfig extends YourRealConfig {


   @Bean
   public HelperA getHelperA() {
       return mock(HelperA.class);
   }

}

In your test class, you can @Autowire HelperA like normal, but it will actually be mocked by Mockito in that test.

Answer 2

If you ONLY want helperB, then you'll need @InjectMocks .

@RunWith(MockitoJUnitRunner.class)
public class MyTest() {

@InjectMocks
public ToBeTested toBeTested;

@Mock 
private HelperB helperB;

...your tests go here

}

Of course, this will leave your helperA null . If you want to have both, you will simply need a Spring configuration for your tests, set helperB as a mock bean (via factory methods) and run the whole thing with the SpringJUnit4ClassRunner )