Writing unit test for file uploader in Junit/Mockito

Question

I am trying to write a unit test for following component to upload file:

@Component("uploader")
public class FileUploader {

  public List<FileItem> processFileUploadRequest(HttpServletRequest request) throws FileUploadException {
    DiskFileItemFactory factory = new DiskFileItemFactory();
    ServletContext servletContext = request.getServletContext();
    File repository = (File) servletContext.getAttribute("javax.servlet.context.tempdir");
    factory.setRepository(repository);
    ServletFileUpload upload = new ServletFileUpload(factory);
    return upload.parseRequest(request);
  }
}

I have written unit test using junit/mockito like following:

@Test
public void testProcessFileUploadRequestSuccess() throws FileUploadException {
    HttpServletRequest request = Mockito.mock(HttpServletRequest.class);
    ServletContext servletContext = Mockito.mock(ServletContext.class);
    Mockito.when(request.getServletContext()).thenReturn(servletContext);
    Mockito.when(servletContext.getAttribute("javax.servlet.context.tempdir")).thenReturn(this.servletTmpDir);
    Assert.assertNotNull(fileUploader.processFileUploadRequest(request));
}

I am getting the following error:

org.apache.commons.fileupload.FileUploadBase$InvalidContentTypeException: the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is null
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:947)
...

Can anyone please give any clue regarding this? Thank you.

Answer 1

This error ...

the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is null

... is a result of your HttpServletRequest not having a multipart content type.

You can fix this by adding the following line to your test case:

Mockito.when(request.getContentType()).thenReturn("multipart/form-data; boundary=someBoundary");

Ona side note: your question (specifically, this part: @Component("uploader")) suggests that you are using Spring. If so, then perhaps your file upload code could be more easily tested using Spring's MockMvcRequestBuilders#fileUpload(String, Object...) to return a MockMultipartHttpServletRequestBuilder. Something like this:

mockMvc.perform(MockMvcRequestBuilders.fileUpload("/upload")
    .file(aFile)
    .andExpect(status().is(200))
    .andExpect(content().string("..."));