class_docstr: Test case for downloading an hrit tarball.
class_docstr_tok: ["Test","case","for","downloading","an","hrit","tarball","."]
docstr: Test downloading a subset of files.
docstr_tok: ["Test","downloading","a","subset","of","files","."]
code: def test_download_a_subset_of_files(self):
      """Test downloading a subset of files."""
      from satpy.demo import download_seviri_hrit_20180228_1500
  
      with mock_filesystem():
          files = download_seviri_hrit_20180228_1500(
              subset={"HRV": [1, 2, 3], "IR_108": [1, 2], "EPI": None}
          )
          assert set(files) == set(
              os.path.join(self.subdir, filename)
              for filename in [
                  "H-000-MSG4__-MSG4________-_________-EPI______-201802281500-__",
                  "H-000-MSG4__-MSG4________-HRV______-000001___-201802281500-__",
                  "H-000-MSG4__-MSG4________-HRV______-000002___-201802281500-__",
                  "H-000-MSG4__-MSG4________-HRV______-000003___-201802281500-__",
                  "H-000-MSG4__-MSG4________-IR_108___-000001___-201802281500-__",
                  "H-000-MSG4__-MSG4________-IR_108___-000002___-201802281500-__",
              ]
          )
  
imports: from __future__ import annotations
  import contextlib
  import io
  import os
  import sys
  import tarfile
  import unittest
  from collections import defaultdict
  from unittest import mock
  import pytest
label_desc: Use image node_id 5 for calling the TestSEVIRIHRITDemoDownload obj's underlying member method code with example usage: obj.test_download_a_subset_of_files() without return types