public static HiveTxnManager swapTxnManager(HiveTxnManager txnMgr) {
    return SessionState.get().setTxnMgr(txnMgr);
  }
Tests to check the ACID properties and isolation level requirements.
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/TestDbTxnManagerIsolationProperties.java