class_docstr: Test case for the downloading and preparing LUTs.
docstr: Fake download of LUT tar file by creating a local tar.
docstr_tok: ["Fake","download","of","LUT","tar","file","by","creating","a","local","tar","."]
code: def mocked_ftp_dl(fname):
      """Fake download of LUT tar file by creating a local tar."""
      import os
      import tarfile
      import tempfile
  
      with tarfile.open(fname, "w:gz") as tar_handle:
          for namer in AHI_LUT_NAMES:
              tmpf = os.path.join(tempfile.tempdir, namer)
              with open(tmpf, "w") as tmp_fid:
                  tmp_fid.write("TEST\n")
              tar_handle.add(tmpf, arcname="count2tbb_v102/" + namer)
              os.remove(tmpf)
  
imports: import os
  import shutil
  import tempfile
  import unittest
  from unittest import mock
  import dask.array
  import numpy
  import pytest
  from pyresample.geometry import AreaDefinition
  from satpy.readers.ahi_l1b_gridded_bin import AHI_LUT_NAMES, AHIGriddedFileHandler
label_desc: Use image node_id 1 for calling the TestAHIGriddedLUTs obj's underlying member method code with example usage: obj.mocked_ftp_dl(fname) without return types