[Bug fix] update name mapping in Transaction.update_schema (#508)

Author: sungwy

pyiceberg/table/__init__.py

@@ -321,7 +321,12 @@ def update_schema(self, allow_incompatible_changes: bool = False, case_sensitive
         Returns:
             A new UpdateSchema.
         """
-        return UpdateSchema(self, allow_incompatible_changes=allow_incompatible_changes, case_sensitive=case_sensitive)
+        return UpdateSchema(
+            self,
+            allow_incompatible_changes=allow_incompatible_changes,
+            case_sensitive=case_sensitive,
+            name_mapping=self._table.name_mapping(),
+        )
 
     def update_snapshot(self) -> UpdateSnapshot:
         """Create a new UpdateSnapshot to produce a new snapshot for the table.

tests/integration/test_rest_schema.py

@@ -672,17 +672,21 @@ def test_rename_simple(simple_table: Table) -> None:
     with simple_table.update_schema() as schema_update:
         schema_update.rename_column("foo", "vo")
 
+    with simple_table.transaction() as txn:
+        with txn.update_schema() as schema_update:
+            schema_update.rename_column("bar", "var")
+
     assert simple_table.schema() == Schema(
         NestedField(field_id=1, name="vo", field_type=StringType(), required=False),
-        NestedField(field_id=2, name="bar", field_type=IntegerType(), required=True),
+        NestedField(field_id=2, name="var", field_type=IntegerType(), required=True),
         NestedField(field_id=3, name="baz", field_type=BooleanType(), required=False),
         identifier_field_ids=[2],
     )
 
     # Check that the name mapping gets updated
     assert simple_table.name_mapping() == NameMapping([
         MappedField(field_id=1, names=['foo', 'vo']),
-        MappedField(field_id=2, names=['bar']),
+        MappedField(field_id=2, names=['bar', 'var']),
         MappedField(field_id=3, names=['baz']),
     ])