Testing @Cacheable in a spring boot test: Caffeine cache not invoked on MockBean

Question

I want to test a service level method that is cached by the @Cacheable annotation. I am mocking the service using Mockito. Below is my cache config and actual test

The cache has not been used and the Mockito verify fails with the method being called twice (instead of once)

My cache config:

@Configuration
@EnableCaching
public class CacheConfiguration implements CachingConfigurer {

    private static final Log LOG = LogFactory.getLog(CacheConfiguration.class);

    @Override
    @Bean
    public CaffeineCacheManager cacheManager() {
        CaffeineCacheManager caffeineCacheManager = new CaffeineCacheManager(
            "sample-cache");
        caffeineCacheManager.setCaffeine(caffeineCacheBuilder());
        caffeineCacheManager.setAllowNullValues(false);
        return caffeineCacheManager;
    }

    Caffeine<Object, Object> caffeineCacheBuilder() {
        return Caffeine.newBuilder().maximumSize(50)
            .expireAfterAccess(30, TimeUnit.MINUTES).softValues();
}

Test:

@RunWith(SpringRunner.class)
@SpringBootTest(classes = *Application.class)
@AutoConfigureMockMvc
public class CachingIntegrationTest {

    @MockBean
    private Service service;

    @Before
    public void setUp() throws {

        Mockito.reset(service);
        String eg = "eg"''

        Mockito.when(service.serviceMethod(argument))
        .thenReturn(eg);

    }

    @Test
    public void verifyCache() throws {

        service.serviceMethod(argument);

        service.serviceMethod(argument);
        Mockito.verify(service, Mockito.times(1)).serviceMethod(argument);

    }

Answer 1

I don't know for sure, but I'd be surprised if @Cacheable annotations still work even if don't actually use the annotated object but instead a Mockito mock of it. The reason is that both techniques (ie the aspect-oriented programming annotation @Cacheable and mocking) are implemented with Java dynamic proxies (or equivalent bytecode generation), so they are likely to get in each other's way.

What you should do instead is mock the collaborators of your service, and then check the number of invocations on these.