private Path getDataTestDir() {
    if (this.dataTestDir == null) {
      setupDataTestDir();
    }
    return new Path(this.dataTestDir.getAbsolutePath());
  }
@return Where to write test data on local filesystem, specific to the test. Useful for tests
        that do not use a cluster. Creates it if it does not exist already.
hbase-diagnostics/src/main/java/org/apache/hadoop/hbase/util/WALPerformanceEvaluationUtil.java