### Question:
MessageMoveRequest implements Serializable { public String validationMessage() { this.src = StringUtils.clean(src); if (StringUtils.isEmpty(src)) { return "Source cannot be empty."; } this.dst = StringUtils.clean(dst); if (StringUtils.isEmpty(dst)) { return "Destination cannot be empty."; } if (src.equals(dst)) { return "Source and Destination cannot be same."; } if (DataType.isUnknown(srcType)) { return "Source data type cannot be unknown."; } if (DataType.isUnknown(dstType)) { return "Destination data type cannot be unknown."; } List<DataType> dataTypes = DataType.getEnabledDataTypes(); if (!dataTypes.contains(srcType)) { return "Source data type is not supported."; } if (!dataTypes.contains(dstType)) { return "Destination data type is not supported."; } return null; } MessageMoveRequest(String src, DataType srcType, String dst, DataType dstType); String validationMessage(); int getMessageCount(RqueueWebConfig rqueueWebConfig);  }### Answer:
@Test public void validationMessage() { MessageMoveRequest request = new MessageMoveRequest(); assertEquals("Source cannot be empty.", request.validationMessage()); request.setSrc(" "); assertEquals("Source cannot be empty.", request.validationMessage()); request.setSrc("job-dlq"); assertEquals("Destination cannot be empty.", request.validationMessage()); request.setDst(" "); assertEquals("Destination cannot be empty.", request.validationMessage()); request.setDst("job-dlq"); assertEquals("Source and Destination cannot be same.", request.validationMessage()); request.setDst("job"); assertEquals("Source data type cannot be unknown.", request.validationMessage()); request.setSrcType(DataType.KEY); assertEquals("Destination data type cannot be unknown.", request.validationMessage()); request.setDstType(DataType.SET); assertEquals("Source data type is not supported.", request.validationMessage()); request.setSrcType(DataType.LIST); assertEquals("Destination data type is not supported.", request.validationMessage()); request.setDstType(DataType.LIST); assertNull(request.validationMessage()); }