def METHOD_NAME(self):
    # Note: Boolean fields are always valid - either False or True
    # That's why the only way to make the notify formset invalid is to
    # reference a non-existing email_settings ID !!!
    data = self.request.copy()
    data["email_settings-0-id"] = -1
    del data["email_settings-0-auto_to_plan_author"]
    response = self.client.post(self.location, data)
    self.assertContains(response, _("Create new TestPlan"))
    self.assertContains(
        response,
        '<input class="bootstrap-switch" name="email_settings-0-auto_to_plan_author" '
        'type="checkbox"',
        html=False,
    )