@Test
  public void testSingleOpen() throws MetaException {
    OpenTxnRequest openTxnRequest = new OpenTxnRequest(1, "me", "localhost");
    long txnId = txnHandler.openTxns(openTxnRequest).getTxn_ids().get(0);
    Assert.assertEquals(1, txnId);
  }
Test openTxn and getOpenTxnList calls on TxnStore.
standalone-metastore/metastore-server/src/test/java/org/apache/hadoop/hive/metastore/txn/TestOpenTxn.java