class_docstr: Unit tests for calibration.
class_docstr_tok: ["Unit","tests","for","calibration","."]
docstr: Create a mocked file handler.
docstr_tok: ["Create","a","mocked","file","handler","."]
code: def file_handler(self):
      """Create a mocked file handler."""
      prolog = {
          "RadiometricProcessing": {
              "Level15ImageCalibration": {
                  "CalSlope": self.gains_nominal,
                  "CalOffset": self.offsets_nominal,
              },
              "MPEFCalFeedback": {
                  "GSICSCalCoeff": self.gains_gsics,
                  "GSICSOffsetCount": self.offsets_gsics,
              },
          },
          "ImageDescription": {
              "Level15ImageProduction": {
                  "PlannedChanProcessing": self.radiance_types
              }
          },
          "ImageAcquisition": {
              "PlannedAcquisitionTime": {
                  "TrueRepeatCycleStart": self.scan_time,
              }
          },
      }
      epilog = {
          "ImageProductionStats": {
              "ActualScanningSummary": {
                  "ForwardScanStart": self.scan_time
              }
          }
      }
      mda = {
          "image_segment_line_quality": {
              "line_validity": np.array([3, 3]),
              "line_radiometric_quality": np.array([4, 4]),
              "line_geometric_quality": np.array([4, 4]),
          },
      }
  
      with mock.patch(
          "satpy.readers.seviri_l1b_hrit.HRITMSGFileHandler.__init__",
          return_value=None,
      ):
          fh = HRITMSGFileHandler()
          fh.platform_id = self.platform_id
          fh.mda = mda
          fh.prologue = prolog
          fh.epilogue = epilog
          return fh
  
imports: import unittest
  from datetime import datetime
  from unittest import mock
  import numpy
  import pytest
  import xarray
  from numpy import testing
  from pyproj import CRS
  import satpy.tests.reader_tests.test_seviri_l1b_hrit_setup
  from satpy.readers.seviri_l1b_hrit import HRITMSGEpilogueFileHandler, HRITMSGFileHandler, HRITMSGPrologueFileHandler
  from satpy.tests.reader_tests.test_seviri_base import ORBIT_POLYNOMIALS_INVALID
  from satpy.tests.reader_tests.test_seviri_l1b_calibration import TestFileHandlerCalibrationBase
  from satpy.tests.utils import assert_attrs_equal, make_dataid
label_desc: Use image node_id 1 for calling the TestHRITMSGCalibration obj's underlying member method code with example usage: obj.file_handler() and returns: fh