Nits

- Raise on missing snapshot in `is_parent_ancestor_of`.
- Add empty-range integration test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: smaheshwar-pltr

pyiceberg/table/snapshots.py

@@ -457,10 +457,14 @@ def ancestors_between_ids(
 
 
 def is_parent_ancestor_of(snapshot_id: int, ancestor_parent_snapshot_id: int, table_metadata: TableMetadata) -> bool:
-    """Return whether any ancestor of ``snapshot_id`` has ``ancestor_parent_snapshot_id`` as its parent."""
+    """Return whether any ancestor of ``snapshot_id`` has ``ancestor_parent_snapshot_id`` as its parent.
+
+    Raises:
+        ValueError: if ``snapshot_id`` is not present in the table metadata.
+    """
     snapshot = table_metadata.snapshot_by_id(snapshot_id)
     if snapshot is None:
-        return False
+        raise ValueError(f"Cannot find snapshot: {snapshot_id}")
     for ancestor in ancestors_of(snapshot, table_metadata):
         if ancestor.parent_snapshot_id == ancestor_parent_snapshot_id:
             return True

tests/integration/test_reads.py

@@ -1309,6 +1309,20 @@ def test_incremental_append_scan_ignores_non_append_snapshots(catalog: Catalog)
     assert sorted(scan.to_arrow()["number"].to_pylist()) == [2, 3, 4]
 
 
+@pytest.mark.integration
+@pytest.mark.parametrize("catalog", [lf("session_catalog_hive"), lf("session_catalog")])
+def test_incremental_append_scan_empty_range(catalog: Catalog) -> None:
+    test_table = catalog.load_table("default.test_incremental_read")
+
+    # snapshots[3] is the only snapshot in the range and is a delete; the scan must return empty.
+    scan = test_table.incremental_append_scan(
+        from_snapshot_id_exclusive=test_table.snapshots()[2].snapshot_id,
+        to_snapshot_id_inclusive=test_table.snapshots()[3].snapshot_id,
+    )
+    assert list(scan.plan_files()) == []
+    assert len(scan.to_arrow()) == 0
+
+
 @pytest.mark.integration
 @pytest.mark.parametrize("catalog", [lf("session_catalog_hive"), lf("session_catalog")])
 def test_incremental_append_scan_schema_evolution_within_range(catalog: Catalog) -> None:

tests/table/test_snapshots.py

@@ -490,6 +490,9 @@ def test_is_parent_ancestor_of(table_v2: Table) -> None:
     assert not is_parent_ancestor_of(ancestor_snapshot_id, snapshot_id, table_v2.metadata)
     # An ID not referenced anywhere in the chain is not a parent ancestor.
     assert not is_parent_ancestor_of(snapshot_id, 42, table_v2.metadata)
+    # Raises when the start snapshot ID is missing from metadata.
+    with pytest.raises(ValueError, match="Cannot find snapshot: 42"):
+        is_parent_ancestor_of(42, snapshot_id, table_v2.metadata)
 
 
 def test_ancestors_between_ids(table_v2: Table) -> None: