@After
  public void tearDown() {
    DistributedSystem ds = InternalDistributedSystem.getAnyInstance();
    if (ds != null) {
      ds.disconnect();
    }
  }
This class makes sure an isolated "loner" distribution manager can be created and do some cache
functions.
geode-core/src/integrationTest/java/org/apache/geode/LonerDMJUnitTest.java