Spring Boot test tries to initialize cache2k for the 2nd time and fails

Question

After adding cache2k to my project some @SpringBootTest's stopped working with an error:

java.lang.IllegalStateException: Cache already created: 'cache'

Below I provide the minimal example to reproduce:

Go to start.spring.io and create a simplest Maven project with Cache starter, then add cache2k dependencies:

<properties>
    <java.version>1.8</java.version>
    <cache2k-version>1.2.2.Final</cache2k-version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.cache2k</groupId>
        <artifactId>cache2k-api</artifactId>
        <version>${cache2k-version}</version>
    </dependency>
    <dependency>
        <groupId>org.cache2k</groupId>
        <artifactId>cache2k-core</artifactId>
        <version>${cache2k-version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.cache2k</groupId>
        <artifactId>cache2k-spring</artifactId>
        <version>${cache2k-version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-cache</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

Now configure the simplest cache:

@SpringBootApplication
@EnableCaching
public class CachingDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(CachingDemoApplication.class, args);
    }

    @Bean
    public CacheManager springCacheManager() {
        SpringCache2kCacheManager cacheManager = new SpringCache2kCacheManager();
        cacheManager.addCaches(b -> b.name("cache"));
        return cacheManager;
    }

}

And add any service (which we will @MockBean in one of our tests:

@Service
public class SomeService {
    public String getString() {
        System.out.println("Executing service method");
        return "foo";
    }
}

Now two @SpringBootTest tests are required to reproduce the issue:

@SpringBootTest
@RunWith(SpringRunner.class)
public class SpringBootAppTest {

    @Test
    public void getString() {
        System.out.println("Empty test");
    }
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class WithMockedBeanTest {

    @MockBean
    SomeService service;

    @Test
    public void contextLoads() {
    }
}

Notice that the 2nd test has mocked @MockBean. This causes an error (stacktrace below).

Caused by: java.lang.IllegalStateException: Cache already created: 'cache'
    at org.cache2k.core.CacheManagerImpl.newCache(CacheManagerImpl.java:174)
    at org.cache2k.core.InternalCache2kBuilder.buildAsIs(InternalCache2kBuilder.java:239)
    at org.cache2k.core.InternalCache2kBuilder.build(InternalCache2kBuilder.java:182)
    at org.cache2k.core.Cache2kCoreProviderImpl.createCache(Cache2kCoreProviderImpl.java:215)
    at org.cache2k.Cache2kBuilder.build(Cache2kBuilder.java:837)
    at org.cache2k.extra.spring.SpringCache2kCacheManager.buildAndWrap(SpringCache2kCacheManager.java:205)
    at org.cache2k.extra.spring.SpringCache2kCacheManager.lambda$addCache$2(SpringCache2kCacheManager.java:143)
    at java.util.concurrent.ConcurrentHashMap.compute(ConcurrentHashMap.java:1853)
    at org.cache2k.extra.spring.SpringCache2kCacheManager.addCache(SpringCache2kCacheManager.java:141)
    at org.cache2k.extra.spring.SpringCache2kCacheManager.addCaches(SpringCache2kCacheManager.java:132)
    at com.example.cachingdemo.CachingDemoApplication.springCacheManager(CachingDemoApplication.java:23)
    at com.example.cachingdemo.CachingDemoApplication$$EnhancerBySpringCGLIB$$2dce99ca.CGLIB$springCacheManager$0(<generated>)
    at com.example.cachingdemo.CachingDemoApplication$$EnhancerBySpringCGLIB$$2dce99ca$$FastClassBySpringCGLIB$$bbd240c0.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363)
    at com.example.cachingdemo.CachingDemoApplication$$EnhancerBySpringCGLIB$$2dce99ca.springCacheManager(<generated>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
    ... 52 more

If you remove @MockBean, both tests will pass.

How can I avoid this error in my test suite?

Answer 1

Your second test represents a different ApplicationContext altogether so the test framework will initiate a dedicated one for it. If cache2k is stateful (for instance sharing the CacheManager for a given classloader if it already exists), the second context will attempt to create a new CacheManager while the first one is still active.

You either need to flag one of the test as dirty (see @DirtiesContext) which will close the context and shut down the CacheManager, or you can replace the cache infrastructure by an option that does not require all that, see @AutoConfigureCache.

If cache2k works in such a way that it requires you to dirty the context, I'd highly recommend to swap it using the later options.