How to fetch a field class from a specific form in Django?

Question

I'm trying to write a test for the username field and I want to use SimpleTestCase.assertFieldOutput(). The problem is that I cannot get the fieldclass from the field of my form:

import django
from django.test import TestCase

    class UserRegistrationTest(TestCase):
    """Tests for the user registration page."""

    def test_username_field(self):
        data = {'username': 'павел25',
                'password1': 'njkdpojv34',
                'password2': 'njkdpojv34',
                'email': '[email protected]',
                'first_name': 'Pavel',
                'last_name': 'Shlepnev'}
        f = RegistrationForm(data)
        self.assertFieldOutput(f.fields['username'], {'pavel25': 'pavel25'}, {'павел25': ['Имя пользователя должно содержать только символы ASCII.']})

When I run the test it raises TypeError: 'UsernameField' object is not callable

Answer 1

Wrapping in type() function seems to work. It gives me a class object which is what I need in the fieldclass argument in SimpleTestCase.assertFieldOutput().

>>> type(f.fields['username'])
<class 'django.contrib.auth.forms.UsernameField'>

The test runs with no errors and produces valid output:

import django
from django.test import TestCase

class UserRegistrationTest(TestCase):
"""Tests for the user registration page."""

    def test_username_field(self):
        data = {'username': 'павел25',
                'password1': 'njkdpojv34',
                'password2': 'njkdpojv34',
                'email': '[email protected]',
                'first_name': 'Pavel',
                'last_name': 'Shlepnev'}
        f = RegistrationForm(data)
        self.assertFieldOutput(type(f.fields['username']), {'pavel25': 'pavel25'}, {'павел25': ['Имя пользователя должно содержать только символы ASCII.']})

    ======================================================================
    FAIL: test_username_field (accounts.tests.UserRegistrationTest)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "C:\Users\pavel\source\repos\Speak the Truth\accounts\tests.py", line 43, in test_username_field
        self.assertFieldOutput(type(f.fields['username']), {'pavel25': 'pavel25'}, {'павел25': ['Имя пользователя должно содержать только символы ASCII.']})
      File "C:\Users\pavel\source\repos\Speak the Truth\env\lib\site-packages\django\test\testcases.py", line 760, in assertFieldOutput
        required.clean(input)
    AssertionError: ValidationError not raised

    ----------------------------------------------------------------------