Question

I’m pretty new to Mockito and mocking out servlets for testing. I’m having problems mocking out an HttpServletRequest which sends some form data to my servlet as a MimeMultiPart. In my servlet I call request.getInputStream() as follows:

mimeMultiPart = new MimeMultipart(new ByteArrayDataSource(
                request.getInputStream(), Constants.MULTI_PART_FORM_DATA));

When I mock out my input stream I create an entire MimeMultiPart message and then I try to return a ServletInputStream from it in the code below

    //Helper function to create ServletInputStream
private ServletInputStream createServletInputStream(Object object)
        throws Exception {

    //create output stream
    ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
    ObjectOutputStream outStream = new ObjectOutputStream(byteOut);

    //this part no workey
    outStream.writeObject(object);

    //create input stream
    final InputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());

    //create a new ServletInputStream and return it
    return new ServletInputStream() {

        @Override
        public int read() throws IOException {
            return byteIn.read();
        }
    };
}

@Test
public void testDoPost() throws Exception {
    PrintWriter writer;
    writer = new PrintWriter("testSendMultiPartBatchResponse.txt");
    when(response.getWriter()).thenReturn(writer);

            //this is the mocked request
    when(request.getInputStream()).thenReturn(
            createServletInputStream(multiPartResponse));

. . . 

now when I run this test I receive the following error on outStream.writeObject(object):

java.io.NotSerializableException: javax.mail.internet.MimeMultipart
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)

    . . . 

it’s not necessary to post the rest of the stack trace, I’m pretty sure the problem is that MimeMultiPart is not serializable, but I don’t know how to rectify this. Is there another way to mock out the request? I am at a loss 🙁

Answer 1

I think this should work:

final ByteArrayOutputStream os = new ByteArrayOutputStream ();
multiPartResponse.writeTo (os);
final ByteArrayInputStream is = new ByteArrayInputStream (os.toByteArray ());
when(request.getInputStream()).thenReturn(new ServletInputStream() {
        @Override
        public int read() throws IOException {
            return is.read();
        }
    });