How to unit test a form with a captcha field in django?

I know this is an old post, but django-simple-captcha now has a setting CAPTCHA_TEST_MODE which makes the captcha succeed if you supply the value 'PASSED'. You just have to make sure to send something for both of the captcha input fields:

post_data['captcha_0'] = 'dummy-value'
post_data['captcha_1'] = 'PASSED'
self.client.post(url, data=post_data)

The CAPTCHA_TEST_MODE setting should only be used during tests. My settings.py:

if 'test' in sys.argv:
    CAPTCHA_TEST_MODE = True 

Here's the way I got around it. Import the model that actually holds Captcha info:

from captcha.models import CaptchaStore

First, I check that the test captcha table is empty:

captcha_count = CaptchaStore.objects.count()
self.failUnlessEqual(captcha_count, 0)

After loading the page (in this case, it's a registration page), check that there's a new captcha object instance:

captcha_count = CaptchaStore.objects.count()
self.failUnlessEqual(captcha_count, 1)

Then, I retrieve the captcha instance data and POST that with the form. In my case, the POST expects 'captcha_0' to contain the hashkey, and 'captcha_1' to contain the response.

captcha = CaptchaStore.objects.all()[0]
registration_data = { # other registration data here
                     'captcha_0': captcha.hashkey,
                     'captcha_1': captcha.response }

You may need to tweak this a little if you start with CaptchaStore instances before you run this test. Hope that helps.

I unit tested it by mocking the ReCaptchaField. First, I've added the recaptcha field in the constructor. It cannot be added as a regular field because you won't be able to mock it (once the code is evaluated before the mock is being applied):

class MyForm(forms.ModelForm):

    ...

    def __init__(self, *args, **kwargs):
        # Add captcha in the constructor to allow mock it
        self.fields["captcha"] = ReCaptchaField()

Then, I just replaced the ReCaptchaField by a not required CharField. This way, I'm trusting django-recaptcha will work. I can test only my own stuff:

@mock.patch("trials.forms.ReCaptchaField", lambda: CharField(required=False))
def test_my_stuff(self):
    response = self.client.post(self.url, data_without_captcha)
    self.assert_my_response_fit_the_needs(response)

One solution is have a setting "testing" that is either true or false. And then just

if not testing:
   # do captcha stuff here

It's simple and easy, and an easy toggle.