@Test
  public void testParsingNull() throws Exception {
    assertNull("parse on null data should return null.", MasterAddressTracker.parse(null));
  }
Unit tests that uses ZooKeeper but does not use the master-side methods but rather acts
directly on ZK.
hbase-zookeeper/src/test/java/org/apache/hadoop/hbase/zookeeper/TestMasterAddressTracker.java