add .size to ArrowFile (#1944)

Author: OneSizeFitsQuorum

fsspec/implementations/arrow.py

@@ -223,7 +223,6 @@ def get_file(self, rpath, lpath, **kwargs):
         "readable",
         "writable",
         "close",
-        "size",
         "seekable",
     ],
 )
@@ -241,6 +240,10 @@ def __init__(self, fs, stream, path, mode, block_size=None, **kwargs):
     def __enter__(self):
         return self
 
+    @property
+    def size(self):
+        return self.stream.size()
+
     def __exit__(self, *args):
         return self.close()
 

fsspec/implementations/tests/test_arrow.py

@@ -280,9 +280,8 @@ def test_get_file_seekable_default(fs, remote_dir, tmp_path):
 
     # Test default behavior (seekable=False)
     local_file = tmp_path / "test_default.txt"
-    fs.get_file(remote_dir + "/test_file.txt", str(local_file))
-    with open(local_file, "rb") as f:
-        assert f.read() == data
+    with pytest.raises(OSError, match="only valid on seekable files"):
+        fs.get_file(remote_dir + "/test_file.txt", str(local_file))
 
     # Test with explicit seekable=True
     local_file_seekable = tmp_path / "test_seekable.txt"
@@ -292,11 +291,10 @@ def test_get_file_seekable_default(fs, remote_dir, tmp_path):
 
     # Test with explicit seekable=False
     local_file_not_seekable = tmp_path / "test_not_seekable.txt"
-    fs.get_file(
-        remote_dir + "/test_file.txt", str(local_file_not_seekable), seekable=False
-    )
-    with open(local_file_not_seekable, "rb") as f:
-        assert f.read() == data
+    with pytest.raises(OSError, match="only valid on seekable files"):
+        fs.get_file(
+            remote_dir + "/test_file.txt", str(local_file_not_seekable), seekable=False
+        )
 
 
 def test_cat_file_seekable_override(fs, remote_dir):
@@ -333,7 +331,7 @@ def test_seekable_true_allows_size_method(fs, remote_dir):
     with fs.open(test_file, "rb", seekable=True) as f:
         assert f.seekable() is True
         # Verify size() method works and returns correct size
-        file_size = f.size()
+        file_size = f.size
         assert file_size == len(data)
         # Also verify we can read the data
         assert f.read() == data
@@ -353,6 +351,6 @@ def test_seekable_false_prevents_size_method(fs, remote_dir):
         assert f.seekable() is False
         # Verify size() raises OSError
         with pytest.raises(OSError, match="only valid on seekable files"):
-            f.size()
+            _ = f.size
         # Verify we can still read the data
         assert f.read() == data