Update type hints for Cursor to match PEP 249. (#9299)

synapse/storage/database.py

@@ -158,8 +158,8 @@ class LoggingDatabaseConnection:
     def commit(self) -> None:
         self.conn.commit()
 
-    def rollback(self, *args, **kwargs) -> None:
-        self.conn.rollback(*args, **kwargs)
+    def rollback(self) -> None:
+        self.conn.rollback()
 
     def __enter__(self) -> "Connection":
         self.conn.__enter__()
@@ -244,12 +244,15 @@ class LoggingTransaction:
         assert self.exception_callbacks is not None
         self.exception_callbacks.append((callback, args, kwargs))
 
+    def fetchone(self) -> Optional[Tuple]:
+        return self.txn.fetchone()
+
+    def fetchmany(self, size: Optional[int] = None) -> List[Tuple]:
+        return self.txn.fetchmany(size=size)
+
     def fetchall(self) -> List[Tuple]:
         return self.txn.fetchall()
 
-    def fetchone(self) -> Tuple:
-        return self.txn.fetchone()
-
     def __iter__(self) -> Iterator[Tuple]:
         return self.txn.__iter__()
 
@@ -754,6 +757,7 @@ class DatabasePool:
         Returns:
             A list of dicts where the key is the column header.
         """
+        assert cursor.description is not None, "cursor.description was None"
         col_headers = [intern(str(column[0])) for column in cursor.description]
         results = [dict(zip(col_headers, row)) for row in cursor]
         return results