private void doMessage(String text) {
    Object[] args = new Object[] {text};
    Host host = Host.getHost(0);
    VM vm = host.getVM(0);
    vm.invoke(getClass(), "message", args);
  }
Verify that listener gets called, and exactly once.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/SystemFailureDUnitTest.java