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

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.

Answer 2

Since I do not want any custom behavior in test, but just want to get rid of this error, the solution is to create CacheManager using unique name like this:
#Bean
public CacheManager springCacheManager() {
SpringCache2kCacheManager cacheManager = new SpringCache2kCacheManager("spring-" + hashCode());
cacheManager.addCaches(b -> b.name("cache"));
return cacheManager;
}

Answer 3

I encountered the same error when using cache2k with Spring Dev Tools, and ended up with the following code as the solution:
#Bean
public CacheManager cacheManager() {
SpringCache2kCacheManager cacheManager = new SpringCache2kCacheManager();
// To avoid the "Caused by: java.lang.IllegalStateException: Cache already created:"
// error when Spring DevTools is enabled and code reloaded
if (cacheManager.getCacheNames().stream()
.filter(name -> name.equals("cache"))
.count() == 0) {
cacheManager.addCaches(
b -> b.name("cache")
);
}
return cacheManager;
}