code: def test_iasi_l2_cdr_nc(fake_iasi_l2_cdr_nc_file):
      """Test the IASI L2 CDR NC reader."""
      from satpy import Scene
  
      sc = Scene(
          filenames=[fake_iasi_l2_cdr_nc_file],
          reader=["iasi_l2_cdr_nc"],
      )
      sc.load(["T", "FLG_IASIBAD", "CloudFraction"])
      assert sc["T"].dims == ("y", "x", "vertical_levels")
      assert sc["T"].shape == (3, 4, 5)
      assert sc["T"].attrs["area"].shape == (3, 4)
      (lons, lats) = sc["T"].attrs["area"].get_lonlats()
      np.testing.assert_array_equal(
          lons, np.array([[0, 0, 0, 0], [1, 1, 1, 1], [2, 2, 2, 2]])
      )
      assert np.isnan(sc["T"][0, 0, 0])
      assert sc["FLG_IASIBAD"][0, 0] == 1
      assert sc["CloudFraction"].dtype == np.dtype("uint8")
      assert sc["T"].attrs["units"] == "K"
  
imports: import math
  import os
  import unittest
  import numpy
  import pytest
  import xarray
label_desc: Use image node_id 4 for calling a global function with example usage: test_iasi_l2_cdr_nc(fake_iasi_l2_cdr_nc_file) without return types