Interesting that you don't see a performance problem. What version did you
try? I'm using 0.5.9.
I just re-ran this example to make sure I wasn't imagining it. On the 11th
run, it wedged, not returning, and burning a lot of cpu, presumably trying
to shrink.
It's a larger problem with the real test cases. One test ran for about
eight hours yesterday before I killed it. Hard to tell what it's doing, and
not sure what sort of times I should expect for shrinking larger test cases.
On Wednesday, November 12, 2014 9:05:40 AM UTC-8, Lucas Bradstreet wrote:
>
> I've also had some tricky shrinking type issues with recursive generators
> using bind. I had a play with your generators, using such-that to reduce
> the row/column name length and also preventing some generator shrinking by
> using no-shrink, but I didn't have much luck improving the resulting
> shrinks (though the shrinks did finish in a timely fashion).
>
> You might have more luck if you generated an m x n matrix size
> independently of the matrix itself and feed the size into the matrix
> generator and the samples and probes generators. This may allow the matrix
> size to be shrunk down more easily, while also shrinking the samples and
> probes vectors without them having to be regenerated for ever new matrix
> shrink (i.e. where the matrix size is maintained but the gen/int values
> within it are shrunk).
>
> However, this is all guess work and conjecture, as I don't understand the
> shrinking algorithm well enough, and I haven't tried my suggestion. Also,
> modifying your generators in this way may make your model less general if
> you wish to use it in other ways later.
>
> Cheers
>
> Lucas
>
>
>
> On 12 Nov 2014, at 02:43, Brian Craft <craft...@gmail.com <javascript:>>
> wrote:
>
> Using test.check, I'm finding the shrinking to be very, very slow. Running
> a hundred cases takes a few seconds, unless it hits an error, in which case
> it takes 40-60 minutes to shrink, and the shrinking is not very effective
> (resulting test case is much larger than necessary). Sometimes the
> shrinking is much faster. It behaves a bit like it's occasionally getting
> into a pathological state, or a difficult shrinking scenario.
>
> Are there any docs on generators or the shrinking algorithm that would
> help build tests that shrink more effectively?
>
> The problematic generator builds a randomly-sized matrix of integers, with
> randomly assigned names for the rows and columns. The failure case is when
> either a column or row name is repeated. I expect the slow shrinking has
> something to do with it being rare for the generator to emit the same name
> twice.
>
> ; Generator of randomly sized matrices of random numbers.
> (def gen-matrix
> (gen/bind
> gen/s-pos-int
> (fn [x] (gen/bind
> gen/s-pos-int
> (fn [y] (gen/vector (gen/vector gen/int x) y))))))
>
> ; Generator of matrix with probe and sample ids.
> (def gen-tsv
> (gen/bind
> gen-matrix
> (fn [m]
> (gen/hash-map
> :probes (gen/vector
> (gen/such-that not-empty gen/string-alpha-numeric)
> (count m))
> :samples (gen/vector
> (gen/such-that not-empty gen/string-alpha-numeric)
> (count (first m)))
> :matrix (gen/return m)))))
>
> Shrinking will result in a case like
>
> {:matrix [[1 4 -3] [-4 -3 -5] [-5 2 3] [4 -5 -5] [1 -2 3] [1 4 1]],
> :samples ["0" "0" "0"], :probes ["0" "0" "0" "0" "0" "0"]}
>
> where :samples ["0" "0"] :probes["0"] would do.
>
> The following test will exhibit the behavior, sometimes succeeding,
> sometimes failing quickly, sometimes shrinking for a very long time:
>
> (tc/quick-check 100 (prop/for-all [tsv gen-tsv] (= (count (set (:probes
> tsv))) (count (:probes tsv)))))
>
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