title: Unable to register MBean
body: <p>I am writing integration tests for a spring-boot application, and I am using a base test class for common methods and all the other common stuff. Something like this:</p>
  
  <pre><code>@ActiveProfiles("test")
  @RunWith(SpringRunner.class)
  @SpringBootTest(webEnvironment = ...)
  @Sql(scripts = { "script1.sql", ... }, ...)
  public abstract class ITBase {
  ...
  </code></pre>
  
  <p>I have a file generator, which is autowired into a service, which is autowired into a controller.
  I am testing the controller using RestTemplate.
  I would like to mock the file generator, to return just a random string.</p>
  
  <p>Because it is a spring Bean, I understood I should use @MockBean annotation in my test in this way:</p>
  
  <pre><code>public class ControllerIT extends ITBase {
  
  @MockBean
  private FileGenerator fileGenerator;
  
  @Test
  @Transactional
  public void testSomeTest() {
  ...
  </code></pre>
  
  <p><strong>My problem is:</strong></p>
  
  <p>If I run the given test class, all tests pass. However, if I run all the test classes, I get an <em>UnableToRegisterMBeanException</em>.
  The stacktrace looks like this:</p>
  
  <pre><code>java.lang.IllegalStateException: Failed to load ApplicationContext
  
  at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124)
  at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:83)
  at org.springframework.boot.test.autoconfigure.AutoConfigureReportTestExecutionListener.prepareTestInstance(AutoConfigureReportTestExecutionListener.java:49)
  at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
  at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
  at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
  at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
  at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
  at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
  at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
  at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
  at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
  at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
  at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
  at org.junit.runners.Suite.runChild(Suite.java:128)
  at org.junit.runners.Suite.runChild(Suite.java:27)
  at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
  at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
  at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
  at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
  at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
  at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
  at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
  at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
  at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
  at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
  at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
  Caused by: org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [org.springframework.cloud.context.environment.EnvironmentManager@607624b7] with key 'environmentManager'; nested exception is javax.management.InstanceAlreadyExistsException: com.gd.configurationrepository:name=environmentManager,type=EnvironmentManager
  at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:625)
  at org.springframework.jmx.export.MBeanExporter.registerBeans(MBeanExporter.java:550)
  at org.springframework.jmx.export.MBeanExporter.afterSingletonsInstantiated(MBeanExporter.java:432)
  at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:796)
  at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:861)
  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)
  at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759)
  at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:369)
  at org.springframework.boot.SpringApplication.run(SpringApplication.java:313)
  at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:111)
  at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:98)
  at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:116)
  ... 31 more
  Caused by: javax.management.InstanceAlreadyExistsException: com.gd.configurationrepository:name=environmentManager,type=EnvironmentManager
  at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:437)
  at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerWithRepository(DefaultMBeanServerInterceptor.java:1898)
  at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:966)
  at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:900)
  at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:324)
  at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
  at org.springframework.jmx.support.MBeanRegistrationSupport.doRegister(MBeanRegistrationSupport.java:195)
  at org.springframework.jmx.export.MBeanExporter.registerBeanInstance(MBeanExporter.java:678)
  at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:615)
  ... 43 more
  </code></pre>
  
  <p>*I have no hikari or whatsoever. Just a simple file generator, service and controller.</p>