contents = [
            'Joe,Elliott,joe@defleppard.com,"rock,vocals"',
            'Rick,Savage,ricks@defleppard.com,"rock,rhythm section"',
            'Rick,Allen,ricka@defleppard.com,"rock,rhythm section"',
        ]

        fields = 'first_name,last_name,email,tags'
        uploaded_file = mock.Mock()
        uploaded_file.name = 'filename.csv'
        uploaded_file.read.return_value = '\r\n'.join(contents)
        uploaded_file.__iter__ = mock.Mock(return_value=iter(contents))


< snip >


    fields = upload_obj.fields.split(',')
    dr = csv.DictReader(open(upload_obj.uploaded_file.path, 'rU'), fieldnames=fields)