def METHOD_NAME(self):
    form = self.app.get(
        "/bulk_adding/party/parl.2015-05-07/PP52/",
        user=self.user_who_can_upload_documents,
    ).forms[1]
    form["source"] = "https://example.com/candidates/"
    response = form.submit()
    self.assertContains(response, "Please enter at least one name")