private void initDataDir(Class<?> cls) {
    testDataDir = new File(
        String.format("%s/%s-%d", System.getProperty("build.dir"), cls.getCanonicalName(), System.currentTimeMillis()))
            .getPath();
  }
Get a unique directory for storing test data, which is based on the class name of the caller unit test
and build.dir environment variable (which is set by the surefire plugin, look for root pom.xml).
@param cls
@return
common/src/test/org/apache/hadoop/hive/conf/HiveConfForTest.java