}
	pdb.Mux.Unlock()

	pdb.Close()
	pdb.Mux.Lock()
	defer pdb.Mux.Unlock()
	if len(pdb.Stmts.Keys()) != 0 {
		t.Fatalf("prepared stmt should be empty")
	}
}

func isUsingClosedConnError(err error) bool {
	// https://github.com/golang/go/blob/e705a2d16e4ece77e08e80c168382cdb02890f5b/src/database/sql/sql.go#L2717
	return err.Error() == "sql: statement is closed"
}