[Haskell-cafe] quickcheck for compiler testing
achudnov at gmail.com
Mon Feb 16 18:44:14 UTC 2015
If you just need an example for generating and shrinking arbitrary ASTs,
you can have a look here:
. Note that I use the testing-feat package to generate Gen instances ---
it tends to do better (explore interesting cases earlier) than
handwritten code --- and then fix-up incorrect ASTs (another option is
to simply discard them).
On 02/16/2015 12:33 PM, Maurizio Vitale wrote:
> By 'test size reduction' I mean the 'shrink' function. It seems to me
> (as I said, first Haskell program and no experience with quickcheck)
> that it works nicely with a topdown generation of the test, but I
> don't see how to easily generate correct programs that way.
> Even if you cannot release your tests, maybe you can help me with a
> very simple case. Consider a trivial AST. A program is a possibly
> nested block. Each block is a bunch of declarations of variables and
> some use of them
> data Block = Block [Declaration] [Statement]
> data Declaration = Var String String
> data Statement = Statement Block | Use String
> How one would generate things like:
> Block [Var "a" "int"] [Use "a"] -- here a is declared in the same
> Block  [Statement Block [Var "s" "int"] [Statement Block  [Use
> "s"]]] -- here s is declared in some other visible scope
> Or am I trying to approach the problem from the wrong angle?
> On Mon, Feb 16, 2015 at 12:02 PM, Andrey Chudnov <achudnov at gmail.com
> <mailto:achudnov at gmail.com>> wrote:
> I use QuichCheck for compiler testing where I generate random, but
> well-formed programs and check some high-level syntactic
> properties on results. The QuickCheck instance is open-source (see
> language-ecmascript), but the compiler-test code is closed-source
> at this time. Still, I found that it's not the ultimate answer:
> many properties are hard to formalize, so I have to resort to unit
> tests. I'm not sure what you mean by "how this would play with
> test size reduction". I think it's worth giving a try, but keep in
> mind that you might still need to use unit tests.
> Let me know if you have any questions.
> On 02/16/2015 11:53 AM, Maurizio Vitale wrote:
>> I'm starting to work on my first real haskell program (I've only
>> RWH exercises under my belt) and wondering whether people use
>> quickcheck at all for compiler testing.
>> I've seen uses of quickcheck for testing parsers, but I'm
>> interested in generating well-formed programs (e.g. random
>> programs with all declarations in reasonable random places). This
>> could be used to test passes other than parsing (or even parsing,
>> for languages that needs to distinguish identifiers, like the
>> 'typedef' problem in C/C++).
>> The only thing I can think of, is to use quickcheck for randomly
>> generating statements, go over them and figure out free variables
>> (incl. functions) and generate declarations in random places for
>> them. But I'm not sure how this would play with test size
>> reduction and doesn't look like a nice solution anyhow.
>> Any idea or pointers to examples? or should I give up on
>> quickcheck for this and just do direct testing?
>> Haskell-Cafe mailing list
>> Haskell-Cafe at haskell.org <mailto:Haskell-Cafe at haskell.org>
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