Re: [Caml-list] Test coverage of generated lexers/parsers

[Vincent Jacques <vincent@vincent-jacques.net>]

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Thanks for your interest in this question! I suspected there was no obvious
solution.

I'll switch to Menhir (with Gabriel's experimental patch) and tell you if
it improved my situation.

2016-03-06 23:59 GMT+01:00 Anton Bachin <antonbachin@yahoo.com>:

> If there is a good, general, alternative approach for this, we can support
> it in Bisect_ppx. Unfortunately, I don’t know enough about Menhir to be
> able to propose anything specific at this point.
>
> Best,
> Anton
>
> On Mar 6, 2016, at 16:53, Gabriel Scherer <gabriel.scherer@gmail.com>
> wrote:
>
> This is an interesting question and, as far as I know, there is no good
> solution using existing versions of the interacting tools.
>
> Below very simple patch that will add (*BISECT-IGNORE*) in front of every
> line of code generated by Menhir, except those written by the programmer
> (the "strecthes" in Menhir-speak). It applies cleanly on top of the latest
> released Menhir archive,
>   http://gallium.inria.fr/~fpottier/menhir/menhir-20160303.tar.gz
>
> The patch as-is is obviously a hack: it would need to be a configuration
> option when running menhir, and hard-coding Bisect (or bisect_ppx)'s syntax
> into Menhir is not elegant. One could try to have a configuration option to
> let users write a fixed string (or comment) at the beginning of each
> generated code line, but I'm not sure whether François Pottier (in cc:)
> would consider this is elegant enough. François, would you comment on
> whether this is a direction that seems acceptable to you?
>
> (Bisect support ignoring entire regions at once by using
> (*BISECT-IGNORE-BEGIN*) and (*BISECT-IGNORE-END*); we could try to
> implement that instead of a per-line change, but I suspect that it would be
> slightly harder to implement (you have to hook the beginning of input, end
> of input, and around each user-code insertion) for no real gain.)
>
> Toggling code-coverage semantics by inserting comments is not a very nice
> interface (although rather logical when you think of the level of
> generality required), so it's a bit frustrating that parser generators
> would have to play at this level. It would be better to have a more
> structured, unified interface supported by all the code-coverage tools, but
> to my knowledge no such thing exists.
>
>
> From d595ba5149a314c56623e1735af7678f5f62d525 Mon Sep 17 00:00:00 2001
> From: Gabriel Scherer <gabriel.scherer@gmail.com>
> Date: Sun, 6 Mar 2016 17:43:14 -0500
> Subject: [PATCH] output (*BISECT-IGNORE*) in front of each
>  non-programmer-written line
>
> EXPERIMENTAL PATCH: this should of course be turned into an explicit option
> ---
>  src/printer.ml | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/src/printer.ml b/src/printer.ml
> index ea978bc..714bb08 100644
> --- a/src/printer.ml
> +++ b/src/printer.ml
> @@ -46,6 +46,7 @@ let rawnl f =
>
>  let nl f =
>    rawnl f;
> +  output_string f "(*BISECT-IGNORE*)";
>    output_substring f whitespace 0 !indentation
>
>  let indent ofs producer f x =
> --
> 2.5.0
>
>
>
> On Sun, Mar 6, 2016 at 2:53 PM, Vincent Jacques <
> vincent@vincent-jacques.net> wrote:
>
>> Hello,
>>
>> Does somebody have experience measuring test coverage of generated
>> lexers/parsers?
>>
>> I'm using ocamllex/ocamlyacc [1] (but I can switch to Menhir [2]) to
>> generate a lexer/parser. In my tests, I simply check that some input
>> strings give the ASTs I expect.
>>
>> I usually use Bisect [3] to make sure that my tests cover the code I
>> intended to cover, but in that configuration, Bisect is lost between the
>> .mll/.mly files and the generated .ml files and produces useless reports.
>>
>> How would you measure test coverage in that case?
>>
>> Thanks,
>>
>> [1] http://caml.inria.fr/pub/docs/manual-ocaml/lexyacc.html
>> [2] http://gallium.inria.fr/~fpottier/menhir/
>> [3] http://bisect.x9c.fr/
>> --
>> Vincent Jacques
>> http://vincent-jacques.net
>>
>> "S'il n'y a pas de solution, c'est qu'il n'y a pas de problème"
>>             Devise Shadock
>>
>
> <0001-output-BISECT-IGNORE-in-front-of-each-non-programmer.patch>
>
>
>


-- 
Vincent Jacques
http://vincent-jacques.net

"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème"
            Devise Shadock

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