Narrow scope of exception assertion; document Windows platform guard

Author: c0llab0rat0r

test/functional/test_files.py

@@ -1,5 +1,6 @@
 import os
 import shutil
+import sys
 import tempfile
 
 import pytest
@@ -293,17 +294,20 @@ def test_add_filepattern_from_dirname_recursive_nofwalk(client, cleanup_pins, mo
 	assert conftest.sort_by_key(res) == conftest.sort_by_key(FAKE_DIR_FNPATTERN1_RECURSIVE_HASH)
 
 
-@pytest.mark.skipif(not O_DIRECTORY,
+@pytest.mark.skipif(sys.platform.startswith("win"),
                     reason="Opening directory FDs does not work on Windows")
 def test_add_filepattern_from_dirfd_recursive_nofwalk(client, cleanup_pins, monkeypatch):
 	monkeypatch.setattr(ipfshttpclient.filescanner, "HAVE_FWALK", False)
 
-	with pytest.raises(NotImplementedError):
-		fd: int = os.open(str(FAKE_DIR_PATH), os.O_RDONLY | O_DIRECTORY)
-		try:
+	assert os.path.isdir(FAKE_DIR_PATH)
+
+	# On Windows, this line will fail with PermissionError: [Errno 13] Permission denied
+	fd: int = os.open(str(FAKE_DIR_PATH), os.O_RDONLY | O_DIRECTORY)
+	try:
+		with pytest.raises(NotImplementedError):
 			client.add(fd, pattern=FAKE_DIR_FNPATTERN1, recursive=True)
-		finally:
-			os.close(fd)
+	finally:
+		os.close(fd)
 
 
 @pytest.mark.skipif(not ipfshttpclient.filescanner.HAVE_FWALK,