@Test public void testNotEnoughToCompact() throws Exception {
    int[][] tableData = {{1, 2}, {3, 4}};
    runStatementOnDriver("insert into " + Table.ACIDTBL + "(a,b) " + makeValuesClause(tableData));
    runStatementOnDriver("alter table " + Table.ACIDTBL + " compact 'MAJOR'");

    runWorker(hiveConf);
    assertTableIsEmpty("TXN_COMPONENTS");

    runCleaner(hiveConf);
    assertTableIsEmpty("TXN_COMPONENTS");
  }
Not enough deltas to compact, no need to clean: there is absolutely nothing to do.
ql/src/test/org/apache/hadoop/hive/ql/TestTxnCommands3.java