Allow ls() on single file in arrowFS (#1931)

Author: martindurant

fsspec/implementations/arrow.py

@@ -75,10 +75,13 @@ def ls(self, path, detail=False, **kwargs):
         path = self._strip_protocol(path)
         from pyarrow.fs import FileSelector
 
-        entries = [
-            self._make_entry(entry)
-            for entry in self.fs.get_file_info(FileSelector(path))
-        ]
+        try:
+            entries = [
+                self._make_entry(entry)
+                for entry in self.fs.get_file_info(FileSelector(path))
+            ]
+        except (FileNotFoundError, NotADirectoryError):
+            entries = [self.info(path, **kwargs)]
         if detail:
             return entries
         else:

fsspec/implementations/tests/test_arrow.py

@@ -151,6 +151,17 @@ def test_ls(fs, remote_dir):
     assert dirs == expected
 
 
+def test_ls_one(fs, remote_dir):
+    if remote_dir != "/":
+        remote_dir = remote_dir + "/"
+    fs.mkdir(remote_dir + "dir/")
+    file = remote_dir + "dir/test_one"
+    fs.touch(file)
+
+    out = fs.ls(file, detail=True)
+    assert out[0] == fs.info(file)
+
+
 def test_mkdir(fs, remote_dir):
     if remote_dir != "/":
         remote_dir = remote_dir + "/"