@Test
  public void testScanSystemTable() throws Exception {
    CompletableFuture<Void> renewFuture = mockScanReturnRenewFuture(SYSTEMTABLE_QOS);
    testForTable(TableName.valueOf(SYSTEM_NAMESPACE_NAME_STR, name.getMethodName()), renewFuture,
      Optional.empty());
  }
Confirm that we will set the priority in {@link HBaseRpcController} for several table operations.
hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java