code: def test_header_type(file_content, exp_header_size):
      """Test identification of the file header type."""
      header = create_test_header(
          dataset_id=make_dataid(name="VIS006", resolution=3000),
          earth_model=1,
          is_full_disk=True,
          is_rapid_scan=0,
      )
      if file_content == b"foobar":
          header.pop("15_SECONDARY_PRODUCT_HEADER")
      with mock.patch(
          "satpy.readers.seviri_l1b_native.np.fromfile"
      ) as fromfile, mock.patch(
          "satpy.readers.seviri_l1b_native.recarray2dict"
      ) as recarray2dict, mock.patch(
          "satpy.readers.seviri_l1b_native.NativeMSGFileHandler._get_memmap"
      ) as _get_memmap, mock.patch(
          "satpy.readers.seviri_l1b_native.NativeMSGFileHandler._read_trailer"
      ), mock.patch(
          "builtins.open", mock.mock_open(read_data=file_content)
      ):
          fromfile.return_value = header
          recarray2dict.side_effect = lambda x: x
          _get_memmap.return_value = np.arange(3)
          fh = NativeMSGFileHandler(
              filename=None, filename_info={}, filetype_info=None
          )
          assert fh.header_type.itemsize == exp_header_size
          assert "15_SECONDARY_PRODUCT_HEADER" in fh.header
  
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 8 for calling a global function with example usage: test_header_type(file_content, exp_header_size) without return types