@SpyBean does not work with generics

[lincetto]

I'm trying to unit-testing a Spring batch job inside Spring boot using JUnit.
I wrote this test class where I want to spy the bean ItemReader:

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@ActiveProfiles({"dev", "batch", "test-jobs"})
public class BatchJobTest {

	@Autowired
	private JobLauncherTestUtils jobLauncherTestUtils;
    	
	@Autowired 
	@Qualifier("contactDownloadAckJob")
	private  Job contactDownloadAckTaskJob;

	@SpyBean
	private ItemReader<CrsOscContact> reader;

	@Test
	public void testJob() throws Exception {
		given(this.reader.read()).willReturn(new CrsOscContact());
		//... blah blah blah
	}	
}

When I run this test, it seems that the @SpyBean annotation does not do its job, that should be proxying the ItemReader bean that's already present in the context, and so I obtain the (correct) exception because, as per definition, if the bean is not found it tries to instantiate a new bean of that type (and I have specified an interface) :

org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.batch.item.ItemReader]: Specified class is an interface

I'm pretty sure that the bean (of ItemReader type) is already in the context because :

• debugging, I see that the target bean instantiation is correctly processed
• if I change the @SpyBean annotation to an @Autowired annotation, the instance of previous point is correctly injected

[philwebb]

Could you please provide a sample application that replicates the issue?

[lincetto]

Hi @philwebb, sure!
Here a repo with a sample test application

https://github.com/lincetto/spring-boot-ghissue-7625

[lincetto]

@philwebb I've got it! The problem is the use of Generics.
If I use Generics

@SpyBean
private ItemReader<String> reader;

I get the exception, if I use

@SpyBean
private ItemReader reader;

the ApplicationContext load successfully and the bean is being spied on.
So it seems that the MockitoPostProcessor (or some sibling component) does not consider the generic type and so finish with trying to create a new instance of that type.
Core Spring instead, starting from version 4.0, consider the generic type when looking for the bean to inject.

[philwebb]

Thanks for the sample. The underlying cause does indeed seem to be the generics. I've raised Spring JIRA SPR-15011 to see if we can improve things.

[jhoeller]

Since this is adressed in the core container in the meantime, does it work for Boot's purposes now?