bug#66776: SRFI-64 test-error doesn't match error types

bug#66776: SRFI-64 test-error doesn't match error types

[Maxim Cournoyer]

Hello,

I've mean meaning to use 'test-error' in test suites, but as a comment
in its source says, it's currently incomplete:

--8<---------------cut here---------------start------------->8---
;; TODO: decide how to specify expected error types for Guile.
--8<---------------cut here---------------end--------------->8---

So, for example, this should fail but passes:

--8<---------------cut here---------------start------------->8---
(use-modules (srfi srfi-64))
(test-begin "test")
(test-error "testing" 'bad (throw 'oops))
(test-end "test")
--8<---------------cut here---------------end--------------->8---

'test-error' report success for any type of exception, which means its 2nd
argument is currently unused.

It'd also be nice if as its second argument it could accept non only a
error symbol key, but an exception type *or* an exception predicate,
e.g.:

--8<---------------cut here---------------start------------->8---
(use-modules (ice-9 exceptions) (srfi srfi-64))

(define-exception-type &my-exception
  &exception                            ;parent
  make-my-exception                     ;constructor
  my-exception?)                        ;predicate

(test-begin "test-error exception types")

;; Passes, but should fail.
(test-error "&my-exception raised"
  &my-exception
  (raise-exception (make-error)))

;; OR

;; Unimplemented, but passes also.
(test-error "&my-exception raised"
  my-exception?
  (raise-exception (make-error)))

(test-begin "test-error exception types")
--8<---------------cut here---------------end--------------->8---

There is a more modern implementation of SRFI-64 out there for Guile
which may provide clues or be used wholesale, though I haven't tried it:
<https://codeberg.org/taylan/scheme-srfis/src/branch/master/srfi/64>.

-- 
Thanks,
Maxim

bug#66776: SRFI-64 test-error doesn't match error types

[Taylan Kammer]

On 27.10.2023 20:40, Maxim Cournoyer wrote:
> 
> There is a more modern implementation of SRFI-64 out there for Guile
> which may provide clues or be used wholesale, though I haven't tried it:
> <https://codeberg.org/taylan/scheme-srfis/src/branch/master/srfi/64>.
> 

FYI, this is how I check whether a caught error matches the 'type':

(define (error-matches? error type)
  (cond
   ((eq? type #t)
    #t)
   ((condition-type? type)
    (and (condition? error) (condition-has-type? error type)))
   ((procedure? type)
    (type error))
   (else
    (let ((runner (test-runner-get)))
      ((%test-runner-on-bad-error-type runner) runner type error))
    #f)))

Defined on Line 336 in execution.body.scm:

https://codeberg.org/taylan/scheme-srfis/src/branch/master/srfi/64/execution.body.scm#L336

In summary, other than #t to match anything, 'type' can be:

- A SRFI 35 condition-type object

- A procedure, which will be called as a predicate on the error

The predicate case should cover the Guile and R6RS exception systems,
which both simply use predicates to detect condition/exception type
from what I can tell:

https://www.gnu.org/software/guile/manual/html_node/Exception-Objects.html

https://www.gnu.org/software/guile/manual/html_node/rnrs-conditions.html

-- 
Taylan


P.S.: The warning on Codeberg re. invisible Unicode characters is from
using ^L to delineate file sections for navigation with Emacs.