How to create cgi.FieldStorage for testing purposes?

Question

I am creating a utility to handle file uploads in webob-based applications. I want to write some unit tests for it.

My question is - as webob uses cgi.FieldStorage for uploaded files I would like to create a FieldStorage instance in a simple way (without emulating a whole request). What it the minimum code I need to do it (nothing fancy, emulating upload of a text file with "Lorem ipsum" content would be fine). Or is it a better idea to mock it?

Answer 1

Your answer fails in python3. Here is my modification. I'm sure it is not perfect, but at least it works on both python2.7 and python3.5.

from io import BytesIO

def _create_fs(self, mimetype, content, filename='uploaded.txt', name="file"):
    content = content.encode('utf-8')
    headers = {u'content-disposition': u'form-data; name="{}"; filename="{}"'.format(name, filename),
               u'content-length': len(content),
               u'content-type': mimetype}
    environ = {'REQUEST_METHOD': 'POST'}
    fp = BytesIO(content)
    return cgi.FieldStorage(fp=fp, headers=headers, environ=environ)

Answer 2

After some research I came up with something like this:

def _create_fs(mimetype, content):                                              
    fs = cgi.FieldStorage()                                                     
    fs.file = fs.make_file()                                                    
    fs.type = mimetype                                                          
    fs.file.write(content)                                                      
    fs.file.seek(0)                                                             
    return fs             

This is sufficient for my unit tests.