### Question:
MachineResourceReferenceDaoImpl implements MachineResourceReferenceDao { @Override public MachineResourceReference read(String id) { return datastore.get(MachineResourceReference.class, id); } MachineResourceReferenceDaoImpl(Datastore datastore); @Override Long getCount(); @Override boolean create(MachineResourceReference machineResourceReference, WriteConcern writeConcern); @Override com.google.code.morphia.Key<MachineResourceReference> createOrModify(MachineResourceReference machineResourceReference, WriteConcern writeConcern); @Override Iterable<com.google.code.morphia.Key<MachineResourceReference>> createOrModify(Collection<MachineResourceReference> machineResourceReferences, WriteConcern writeConcern); @Override MachineResourceReference read(String id); @Override boolean update(MachineResourceReference machineResourceReference, WriteConcern writeConcern); @Override WriteResult delete(String id); @Override List<MachineResourceReference> getAllMachineResourceReferences(Page page);  }### Answer:
@Test public void testRead() throws Exception { MachineResourceReference processingLimitsFromRead = machineResourceReferenceDao.read(""); assertNull(processingLimitsFromRead); final MachineResourceReference machineResourceReference = new MachineResourceReference("1"); machineResourceReferenceDao.create(machineResourceReference, WriteConcern.NONE); processingLimitsFromRead = machineResourceReferenceDao.read(machineResourceReference.getId()); machineResourceReferenceDao.delete(machineResourceReference.getId()); }