### Question:
MachineDAO extends DefaultDAOBase<Integer, Machine> { public int deleteRackMachines(final Rack rack) { assert rack != null; assert isManaged2(rack); Collection<Machine> machines = findRackMachines(rack); for (Machine machine : machines) { remove(machine); } return machines.size(); } MachineDAO();  MachineDAO(final EntityManager entityManager); List<Machine> findMachines(final Datacenter datacenter); List<Machine> findRackMachines(final Rack rack); List<Machine> findRackMachines(final Rack rack, final String filter); List<Machine> findMachinesWithHAInProgress(); List<Machine> findRackEnabledForHAMachines(final Rack rack); List<Machine> findRackEnabledForHAMachinesInUcs(final UcsRack rack); boolean existsAnyWithDatacenterAndName(final Datacenter datacenter, final String name); boolean existsAnyOtherWithDatacenterAndName(final Machine machine, final String name); int deleteRackMachines(final Rack rack); List<Machine> findCandidateMachines(final Integer idRack,
        final Integer idVirtualDatacenter, final Long hdRequiredOnDatastore,
        final Enterprise enterprise); List<Machine> findCandidateMachines(final Integer idRack,
        final Integer idVirtualDatacenter, final Enterprise enterprise, final String datastoreUuid,
        final Integer originalHypervisorId); List<Machine> findReservedMachines(final Enterprise enterprise); Machine findReservedMachine(final Enterprise enterprise, final Integer machineId); void reserveMachine(final Machine machine, final Enterprise enterprise); void releaseMachine(final Machine machine); Machine findByIds(final Integer datacenterId, final Integer rackId,
        final Integer machineId); Machine findByIp(final Datacenter datacenter, final String ip); Set<Integer> findAllIds(); List<Integer> findAllIdsInDatacenters(final Datacenter... datacenters); Long getTotalUsedCores(); Long getTotalUsedCoresExceptMachine(final Machine machine);  }### Answer:
@Test public void test_deleteRackMachines() { MachineGenerator machineGenerator = new MachineGenerator(getSeed()); Datacenter datacenter = new Datacenter("Datacenter name", "Datacenter location"); Rack rack1 = datacenter.createRack("Rack 1", 2, 4094, 2, 10); Rack rack2 = datacenter.createRack("Rack 2", 2, 4094, 2, 10); Machine machine1_1 = machineGenerator.createMachine(datacenter); machine1_1.setRack(rack1); Machine machine2_1 = machineGenerator.createMachine(datacenter); machine2_1.setRack(rack2); Machine machine2_2 = machineGenerator.createMachine(datacenter); machine2_2.setRack(rack2); Machine machine3 = machineGenerator.createMachine(datacenter); ds().persistAll(datacenter, rack1, rack2, machine1_1, machine2_1, machine2_2, machine3); MachineDAO dao = createDaoForReadWriteTransaction(); Assert.assertEquals(dao.deleteRackMachines(reload(dao, rack1)), 1); EntityManagerHelper.commitAndClose(dao.getEntityManager()); Assert.assertFalse(ds().canFind(machine1_1)); Assert.assertTrue(ds().canFind(machine2_1)); Assert.assertTrue(ds().canFind(machine2_2)); Assert.assertTrue(ds().canFind(machine3)); dao = createDaoForReadWriteTransaction(); Assert.assertEquals(dao.deleteRackMachines(reload(dao, rack2)), 2); EntityManagerHelper.commitAndClose(dao.getEntityManager()); Assert.assertFalse(ds().canFind(machine1_1)); Assert.assertFalse(ds().canFind(machine2_1)); Assert.assertFalse(ds().canFind(machine2_2)); Assert.assertTrue(ds().canFind(machine3)); }