@Test(expected = GemFireConfigException.class)
  public void clientIsPreventedFromConnectingToLocatorAsServer() {
    addIgnoredException("Improperly configured client detected", VM.getLocator());
    ClientCacheFactory clientCacheFactory = new ClientCacheFactory();
    clientCacheFactory.addPoolServer("localhost", DistributedTestUtils.getDUnitLocatorPort());
    clientCacheFactory.setPoolSubscriptionEnabled(true);
    getClientCache(clientCacheFactory);
    Region region = ((ClientCache) cache).createClientRegionFactory(ClientRegionShortcut.PROXY)
        .create(REGION_NAME1);
    region.registerInterest(k1);
  }
bug 35380: Cycling a DistributedSystem with an initialized pool causes interest registration
NPE

Test Scenario:

Create a DistributedSystem (DS1). Create a pool, initialize (creates a proxy with DS1 memberid)
Disconnect DS1. Create a DistributedSystem (DS2). Create a Region with pool, it attempts to
register interest using DS2 memberid, gets NPE.
geode-dunit/src/main/java/org/apache/geode/internal/cache/tier/sockets/ClientServerMiscDUnitTestBase.java