class_docstr: Unit tests for SEVIRI calibration handler.
class_docstr_tok: ["Unit","tests","for","SEVIRI","calibration","handler","."]
docstr: Test initialization of the calibration handler.
docstr_tok: ["Test","initialization","of","the","calibration","handler","."]
code: def test_init(self):
      """Test initialization of the calibration handler."""
      with pytest.raises(
          ValueError,
          match="Invalid calibration mode: INVALID. Choose one of (.*)",
      ):
          SEVIRICalibrationHandler(
              platform_id=None,
              channel_name=None,
              coefs=None,
              calib_mode="invalid",
              scan_time=None,
          )
  
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 1 for calling the TestSeviriCalibrationHandler obj's underlying member method code with example usage: obj.test_init() without return types