How to catch syntax exception

Question

I want to extend srfi-78 by a macro that tests for syntax exception. I want something like this:

#! /usr/bin/env scheme-script
#!r6rs

(import (rnrs) (srfi :78 lightweight-testing))

; the macros I want to test
(define-syntax some-macros
  (syntax-rules ()
    [(_) 'ok]))

; the extension to srfi-78
(define-syntax check-exception
  (syntax-rules ()
        ; ... some code ...
        ))

; tests

; prints "correct" or someting like that
(check (some-macros) => 'ok)

; should print "correct" (i. e. the test passed)
(check-exception (some-macros 'arg)) 

; should print "error"
; (i. e. the exception was not thrown as expected)
(check-exception (some-macros)) 

Is it possible at all? If not, how would you write tests for macroses?

I know about test-read-eval-string from srfi-64. It accepts a string, translates it into a form and evaluates this form in initial environment. I want a macro that evaluates given form in current environment and catches exceptions.

Answer 1

The only portable way to do this is, is to call the code via eval, and wrap that in a guard.

Eg:

(define (safe-eval code env)
  (guard [e [(syntax-violation? e) (display e)]]
    (eval code env)))

Usage:

> (safe-eval '(let a v) (environment '(rnrs)))
&who: let
&message: "invalid syntax"
&syntax:
  form: (let a v)
  subform: #f