[Haskell-cafe] Quickcheck research

wren ng thornton wren at freegeek.org
Tue Nov 22 18:42:03 CET 2011

On 11/22/11 6:09 AM, Macías López wrote:
> Hello:
> I'm a Master's student in Computer Science. I have to make a project
> involving some research, I'm very interested in Quickcheck and I wonder if
> there are some areas which need work or if there is some potential research
> topic related to it.
> In particular I know that Erlang Quickcheck has been worked on a lot and
> has some features like state machines or C bindings which may be useful to
> the Haskell community.
> I would appreciate any directions.

Something I think would be nice is to see full integration between 
SmallCheck and QuickCheck. In particular, I'd like to use SmallCheck to 
exhaustively search the small cases, and then use QuickCheck in a way 
that ensures that it only tests on things larger than the ones which 
have already been tested.

One of the problems with mixing the two these days is that QuickCheck 
often wastes a lot of time checking things that SmallCheck will also 
test. While the goal may not seem very researchy, it actually gets at 
one of the main weaknesses of QuickCheck: namely, how to properly 
control generation of arbitrary values in order to ensure you're testing 
something helpful. It's too easy to design Arbitrary instances which 
only generate small values (e.g., half of all lists are the empty list) 
or which loop forever (because of trying to avoid the too-small 
problem), which makes me think that Arbitrary isn't the right set of 
abstractions for controlling coverage of the value space.

I haven't followed the Erlang line of QC, so I'm not sure if they've 
made progress on this issue or not.

Live well,

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