@Before
  public void setup() throws Exception {
    m_injector = Guice.createInjector(
        Modules.override(new InMemoryDefaultTestModule()).with(new MockModule()));

    m_injector.getInstance(GuiceJpaInitializer.class);
  }
Tests {@link TransactionalLock} and associated classes.
ambari-server/src/test/java/org/apache/ambari/annotations/TransactionalLockInterceptorTest.java