code: def test_feedback_missing_uid(client):
      response = client.post("/feedback?iid=795&rating=5")
      assert response.status_code == 400
      assert response.data == b"uid is required"
  
file_path: cornac/tests/cornac/serving/test_app.py
imports: import os
  import pytest
  from cornac.data import Reader, Dataset
  from cornac.models import BPR
label_desc: Use image node_id 8 for calling a global function with example usage: test_feedback_missing_uid(client) without return types