add tmpfs and use to test fsspec in get_from_cache

tests/fixtures/fsspec.py

@@ -1,5 +1,6 @@
 import posixpath
 from pathlib import Path
+from unittest.mock import patch
 
 import fsspec
 import pytest
@@ -40,10 +41,6 @@ def info(self, path, *args, **kwargs):
         out["name"] = out["name"][len(self.local_root_dir) :]
         return out
 
-    def get_file(self, rpath, lpath, *args, **kwargs):
-        rpath = posixpath.join(self.local_root_dir, self._strip_protocol(rpath))
-        return self._fs.get_file(rpath, lpath, *args, **kwargs)
-
     def cp_file(self, path1, path2, *args, **kwargs):
         path1 = posixpath.join(self.local_root_dir, self._strip_protocol(path1))
         path2 = posixpath.join(self.local_root_dir, self._strip_protocol(path2))
@@ -77,10 +74,27 @@ def _strip_protocol(cls, path):
         return path
 
 
+class TmpDirFileSystem(MockFileSystem):
+    protocol = "tmp"
+    tmp_dir = None
+
+    def __init__(self, *args, **kwargs):
+        assert self.tmp_dir is not None, "TmpDirFileSystem.tmp_dir is not set"
+        super().__init__(*args, **kwargs, local_root_dir=self.tmp_dir, auto_mkdir=True)
+
+    @classmethod
+    def _strip_protocol(cls, path):
+        path = stringify_path(path)
+        if path.startswith("tmp://"):
+            path = path[6:]
+        return path
+
+
 @pytest.fixture
 def mock_fsspec():
     original_registry = fsspec.registry.copy()
     fsspec.register_implementation("mock", MockFileSystem)
+    fsspec.register_implementation("tmp", TmpDirFileSystem)
     yield
     fsspec.registry = original_registry
 
@@ -89,3 +103,10 @@ def mock_fsspec():
 def mockfs(tmp_path_factory, mock_fsspec):
     local_fs_dir = tmp_path_factory.mktemp("mockfs")
     return MockFileSystem(local_root_dir=local_fs_dir, auto_mkdir=True)
+
+
+@pytest.fixture
+def tmpfs(tmp_path_factory, mock_fsspec):
+    tmp_fs_dir = tmp_path_factory.mktemp("tmpfs")
+    with patch.object(TmpDirFileSystem, "tmp_dir", tmp_fs_dir):
+        yield TmpDirFileSystem()

tests/test_file_utils.py

@@ -36,10 +36,10 @@ def zstd_path(tmp_path_factory):
 
 
 @pytest.fixture
-def mockfs_file(mockfs):
-    with open(os.path.join(mockfs.local_root_dir, FILE_PATH), "w") as f:
+def tmpfs_file(tmpfs):
+    with open(os.path.join(tmpfs.local_root_dir, FILE_PATH), "w") as f:
         f.write(FILE_CONTENT)
-    return mockfs
+    return FILE_PATH
 
 
 @pytest.mark.parametrize("compression_format", ["gzip", "xz", "zstd"])
@@ -99,13 +99,11 @@ def test_cached_path_missing_local(tmp_path):
         cached_path(missing_file)
 
 
-def test_get_from_cache_fsspec(mockfs_file):
-    with patch("datasets.utils.file_utils.fsspec.get_fs_token_paths") as mock_get_fs_token_paths:
-        mock_get_fs_token_paths.return_value = (mockfs_file, "", [FILE_PATH])
-        output_path = get_from_cache("mock://huggingface.co")
-        with open(output_path) as f:
-            output_file_content = f.read()
-        assert output_file_content == FILE_CONTENT
+def test_get_from_cache_fsspec(tmpfs_file):
+    output_path = get_from_cache(f"tmp://{tmpfs_file}")
+    with open(output_path) as f:
+        output_file_content = f.read()
+    assert output_file_content == FILE_CONTENT
 
 
 @patch("datasets.config.HF_DATASETS_OFFLINE", True)