python - how to write unittest in Django for method with ListField variable? -

i have never written unit test before. i'm trying write unit test class:

class user(models.model):     facebook_id = models.charfield(max_length=200)     friends = listfield()     status = models.charfield(max_length=200)     status_time = models.datetimefield('date published')      @staticmethod     def login(cls, userid, facebook_friends):         myuser = none         try:             myuser = user.objects.get(facebook_id=userid)         except user.doesnotexist:             myuser = user()             myuser.status_time = datetime.datetime.now() - datetime.timedelta(minutes=16)             myuser.facebook_id = userid             myuser.save()          # user exists         myuser.friends = facebook_friends         myuser.save()         return {"data":myuser.get_friend_statuses()} 

but i'm not sure how write unit test facebook_friend since it's in list field class:

class listfield(models.textfield):     __metaclass__ = models.subfieldbase     description = "stores python list"      def __init__(self, *args, **kwargs):         super(listfield, self).__init__(*args, **kwargs)      def to_python(self, value):         if not value:             value = []         if isinstance(value, list):             return value         return ast.literal_eval(value)      def get_prep_value(self, value):         if value none:             return value         return unicode(value)      def value_to_string(self, obj):         value = self._get_val_from_obj(obj)         return self.get_db_prep_value(value) 

i tried it's not working , i'm not sure how write it:

 class listfield(models.textfield):      def test_wrong_username(self):          user = user.login(self, 'username1', ['one', 'two', 'three'])          errcode = user.login(self, 'username2', ['one', 'two', 'three'])          self.assertequal(errcode, user) 

can me/show me how write unit test one?

i'm going presume instead of testing facebook_friends want test login method. i'm presuming because example test code telling me.

okay, behaviour want login method

if user given userid exists retrieved database. facebook_friends pass function saved onto friends attribute , return dictionary friends statuses.

if user not exist, create it, set couple of attributes, save , following rest of same code path above. so, unit test user exists code path of login method might this

import unittest mock import patch  class userlogintest(unittest.testcase):      @patch('model.user.get_friend_statuses')     def test_login_when_user_exists(self, mock_get_friend_statuses):          # objects.create creates , saves db entry in 1 step          user.objects.create(facebook_id='an_id')           return_value = user.login('an_id', ['some', 'list', 'items'])           user = user.objects.get(facebook_id='an_id')          self.assertequal(user.friends, ['some', 'list', 'items'])          self.assertequal(              return_value,              {'data' mock_get_friend_statuses.return_value}          )          self.assertisnone(user.status_time)