class_docstr: Test the ViiL1bNCFileHandler reader.
class_docstr_tok: ["Test","the","ViiL1bNCFileHandler","reader","."]
docstr: Test the calibration functions.
docstr_tok: ["Test","the","calibration","functions","."]
code: def test_calibration_functions(self):
      """Test the calibration functions."""
      radiance = np.array([[1.0, 2.0, 5.0], [7.0, 10.0, 20.0]])
  
      cw = 13.0
      a = 3.0
      b = 100.0
      bt = self.reader._calibrate_bt(radiance, cw, a, b)
      expected_bt = np.array(
          [
              [675.04993213, 753.10301462, 894.93149648],
              [963.20401882, 1048.95086402, 1270.95546218],
          ]
      )
      assert np.allclose(bt, expected_bt)
  
      angle_factor = 0.4
      isi = 2.0
      refl = self.reader._calibrate_refl(radiance, angle_factor, isi)
      expected_refl = np.array(
          [
              [62.8318531, 125.6637061, 314.1592654],
              [439.8229715, 628.3185307, 1256.637061],
          ]
      )
      assert np.allclose(refl, expected_refl)
  
file_path: satpy/satpy/tests/reader_tests/test_vii_l1b_nc.py
imports: import datetime
  import os
  import unittest
  import uuid
  import dask.array
  import numpy
  import pytest
  import xarray
  from netCDF4 import Dataset
  from satpy.readers.vii_l1b_nc import ViiL1bNCFileHandler
  from satpy.readers.vii_utils import MEAN_EARTH_RADIUS
label_desc: Use image node_id 3 for calling the TestViiL1bNCFileHandler obj's underlying member method code with example usage: obj.test_calibration_functions() without return types