How to write junit for InMultiPart

How to write junit for InMultiPart

I am using apache wink services for file uploading. i want write down
junit test case for file upload.
Following is my controller class
public Response
updateUserInfo(org.apache.wink.common.model.multipart.InMultiPartinMP)
throws Exception{
while (inMP.hasNext()) {
InPart part = inMP.next();
---------------
---------------
}
}