class_docstr: Tests for getting the dataset.
class_docstr_tok: ["Tests","for","getting","the","dataset","."]
code: def _fake_data():
      num_visir_cols = 5  # will be divided by 1.25 -> 4 columns
      visir_rec = [
          ("line_data", np.uint8, (num_visir_cols,)),
          ("acq_time", time_cds_short),
      ]
      vis006_line1 = (
          [1, 2, 3, 4, 5],  # line_data
          (1, 1000),  # acq_time (days, milliseconds)
      )
      vis006_line2 = ([6, 7, 8, 9, 10], (1, 2000))
      vis006_line3 = ([11, 12, 13, 14, 15], (1, 3000))
      vis006_line4 = ([16, 17, 18, 19, 20], (1, 4000))
      ir108_line1 = ([20, 19, 18, 17, 16], (1, 1000))
      ir108_line2 = ([15, 14, 13, 12, 11], (1, 2000))
      ir108_line3 = ([10, 9, 8, 7, 6], (1, 3000))
      ir108_line4 = ([5, 4, 3, 2, 1], (1, 4000))
      data = np.array(
          [
              [(vis006_line1,), (ir108_line1,)],
              [(vis006_line2,), (ir108_line2,)],
              [(vis006_line3,), (ir108_line3,)],
              [(vis006_line4,), (ir108_line4,)],
          ],
          dtype=[("visir", visir_rec)],
      )
      return data
  
imports: from __future__ import annotations
  import os
  import unittest
  import warnings
  from datetime import datetime
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  import xarray
  from satpy.readers.eum_base import recarray2dict, time_cds_short
  from satpy.readers.seviri_l1b_native import ASCII_STARTSWITH, ImageBoundaries, NativeMSGFileHandler, Padder, get_available_channels, has_archive_header
  from satpy.tests.reader_tests.test_seviri_base import ORBIT_POLYNOMIALS, 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 3 for calling the TestNativeMSGDataset obj's underlying member method code with example usage: obj._fake_data() and returns: data