'``SupervisedRegistrationProfile.send_activation_email`` sends a plain
text email if settings.REGISTRATION_EMAIL_HTML is False.'

def test_admin_approval_email_is_plain_text_if_html_disabled(self):

    settings.REGISTRATION_EMAIL_HTML = False
    new_user = UserModel().objects.create_user(**self.user_info)
    profile = self.registration_profile.objects.create_profile(new_user)
    profile.activated = True
    self.registration_profile.objects.send_admin_approve_email(new_user, Site.objects.get_current())
    self.assertEqual(len(mail.outbox[0].alternatives), 0)
