package stub import ( "errors" "strconv" ) var ( ErrCheck = errors.New("one or more arguments did not match") ) // UniqueError is an error that only equivalates to other [UniqueError] with the same magic value. type UniqueError uintptr func (e UniqueError) Error() string { return "unique error " + strconv.Itoa(int(e)) + " injected by the test suite" } func (e UniqueError) Is(target error) bool { var u UniqueError if !errors.As(target, &u) { return false } return e == u }