behaviour change on ImageField because of django.core.validators.validate_image_file_extension

[rm_]

The following test code snippet stopped working after upgrading django to 1.11 from 1.10.x. The code now raises a validation error because the posted image has not a valid file extension:

class Test(TestCase):
    def test_post(self):
        img = BytesIO(IMAGE)
        data = {
            'image': img,
        }
        response = self.client.post(url, data=data)

The view takes the data and fill the following ModelForm that fails validation:

class Image(models.Model):
    image = models.ImageField(_(u'Immagine'), upload_to='image')


class ImageForm(forms.ModelForm):
    class Meta:
        model = Image

As a workaround, adding a name attribute to the BytesIO object make the code work again:

        img.name = 'ciao.jpg'