@BeforeClass
  public static void setUpBeforeClass() throws Exception {
    // Make block sizes small.
    TEST_UTIL.getConfiguration().setInt("dfs.blocksize", 1024 * 1024);
    // needed for testAppendClose()
    // quicker heartbeat interval for faster DN death notification
    TEST_UTIL.getConfiguration().setInt("dfs.namenode.heartbeat.recheck-interval", 5000);
    TEST_UTIL.getConfiguration().setInt("dfs.heartbeat.interval", 1);
    TEST_UTIL.getConfiguration().setInt("dfs.client.socket-timeout", 5000);

    // faster failover with cluster.shutdown();fs.close() idiom
    TEST_UTIL.getConfiguration().setInt("dfs.client.block.recovery.retries", 1);
    TEST_UTIL.startMiniDFSCluster(3);
  }
WAL tests that can be reused across providers.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/AbstractTestProtobufLog.java