protected static void message(String s) {
    System.out.println(s);
    System.err.println(s);
    org.apache.geode.test.dunit.LogWriterUtils.getLogWriter().info(s);
    cache.getLogger().info(s);
  }
Verify that listener gets called, and exactly once.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/SystemFailureDUnitTest.java