How to write unit test for CommonsMultipartFile with Mock in Spring

Question

I am using spring 3.0 org.springframework.web.multipart.commons.CommonsMultipartFile for file uploading. i want write down unit test case for file upload using Mockito.

Following is my controller class

private RegistrationService registrationService;

@RequestMapping(method = RequestMethod.POST)
    public String create(Registration registration, BindingResult result,ModelMap model)
            throws NumberFormatException, Exception {
        
        File uploadedFile = uploadFile(registration);
        List<Registration> userDetails = new ArrayList<Registration>();
        processUploadedFile(uploadedFile,userDetails);
        
        model.addAttribute("userDetails", userDetails);
        
        return "Registration";
    }
    
    private File uploadFile(Registration registration) {
        
        Date dt = new Date();
        SimpleDateFormat format = new SimpleDateFormat("MM_dd_yyyy_HH_mm_ss");
        File uploadedFile = new File(uploadFileLocation
                + registration.getFileData().getOriginalFilename() + "."
                + format.format(dt));
         
        try {
            registration.getFileData().transferTo(uploadedFile);
            
        } catch (IllegalStateException e) {
            logger.error("Error occurred while uploading file", e);  
        } catch (IOException e) {
            logger.error("Error occurred while uploading file", e);
        }   
        
        return uploadedFile;
    }

    private void processUploadedFile(File uploadedFile, List<Registration> userDetails)
            throws NumberFormatException, Exception {

        registrationService.processFile(uploadedFile, userDetails);
    }

Registration class

public class Registration {
    private String name;
    private CommonsMultipartFile fileData;
    
    
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public CommonsMultipartFile getFileData() {
        return fileData;
    }

    public void setFileData(CommonsMultipartFile fileData) {
        this.fileData = fileData;
    }
}

My Service class method

public void processFile(File uploadedFile,
            List<Registration> userDetails) throws NumberFormatException,
            Exception {     

        String record = "";

        try {

            FileWriter fstream = new FileWriter(outputFileLocation
                    + uploadedFile.getName());
            BufferedWriter out = new BufferedWriter(fstream);

            BufferedReader br = new BufferedReader(new FileReader(
                    uploadedFile.getAbsolutePath()));

            while ((record = br.readLine()) != null) {
                String[] requesterUser = record.split(",");

                if (insertUserToDB(requesterUser, userDetails) > 0)
                    out.write(record + ", Yes");
                else
                    out.write(record + ", No");

                out.newLine();

            }
            out.flush();
            out.close();

        } catch (FileNotFoundException e) {
            logger.error("Error occured while processing file",  e);
        } catch (IOException e) {
            
            logger.error("Error occured while processing file",  e);
        }

        
    }

How to Unit Test it?I am new to Mockito.

Edit

I have write down Test method for testing above code, but it return null for multipartFile. How should I test above service class processFile method?

@Test
       public void testProcessFile() {
        private static final String TEST_FILE = "c:\\user.csv";
        MockMultipartHttpServletRequest request = new MockMultipartHttpServletRequest();
        MockMultipartHttpServletRequest mockMultipartHttpServletRequest = (MockMultipartHttpServletRequest)request;
        MultipartFile multipartFile = (MultipartFile) mockMultipartHttpServletRequest.getFile(TEST_FILE);

        Registration registration=new Registration();
        registration.setFileData(multipartFile);
        RegistrationService.processFile(uploadedFile, userDetails);
        }

I am new to JUnit and mockito. Any help or pointer really appreciated.

Answer 1

You might want to consider using Spring's Mock implementation (org.springframework.mock.web.MockMultipartFile) rather than creating a mock using Mockito.

Answer 2

Heinrich Filter is right, but you also need to change the type for the field fileData from CommonsMulitPartFile to org.springframework.web.multipart.MultipartFile. (This is the super interface above CommonsMulitPartFile and MockMultipartFile.

If you have done this, then you can create a mock of the multipart file itselfe with an mock object that is provided by spring

MockMultipartFile mockMultipartFile = new MockMultipartFile(
    "fileData",
    fileName,
    "text/plain",
    content);