class_docstr: Unit tests for SEVIRI calibration handler.
class_docstr_tok: ["Unit","tests","for","SEVIRI","calibration","handler","."]
docstr: Test selection of gain and offset.
docstr_tok: ["Test","selection","of","gain","and","offset","."]
code: def test_get_gain_offset(self, calib_mode, ext_coefs, expected):
      """Test selection of gain and offset."""
      calib = self._get_calibration_handler(
          calib_mode=calib_mode, ext_coefs=ext_coefs
      )
      coefs = calib.get_gain_offset()
      assert coefs == expected
  
imports: import unittest
  from datetime import datetime
  import numpy
  import pytest
  import xarray
  from satpy.readers.seviri_base import SEVIRICalibrationAlgorithm, SEVIRICalibrationHandler
label_desc: Use image node_id 4 for calling the TestSeviriCalibrationHandler obj's underlying member method code with example usage: obj.test_get_gain_offset(calib_mode, ext_coefs, expected) without return types