code: def test_gray2lab():
      cv_gray = cv.imread(tens_path)
      cv_gray = cv.cvtColor(cv_gray, cv.COLOR_BGR2GRAY)
      cv_gray = caer.to_tensor(cv_gray, cspace="gray")
  
      lab = caer.gray2lab(cv_gray)
  
      assert len(lab.shape) == 3
      assert isinstance(lab, caer.Tensor)
      assert lab.is_lab()
  
file_path: caer/tests/color/test_gray.py
imports: import caer
  import cv2
  import os
label_desc: Use image node_id 5 for calling a global function with example usage: test_gray2lab() without return types