Hi
I would like to test a function which recursively traverses the nodes in a
graph and collects them. For example,
(def graph {1 [2 3 4]
2 [5 6 7]
6 [8 9]
10 [11 12 13]}
my function is given a starting point say, 1 and should then traverse each
node which is reachable and return the set. In this case the result should
be:
#{3, 4, 5, 7, 8, 9}
note: it does not return any elements reachable by 10.
I would like to test this using test.check, but I would like to generate
test data which will exercise the traversal of the graph.
I found a similar thread here:
https://groups.google.com/forum/#!topic/clojure/YWeT8BFc8k4
But, I don't think the proposed solution would suit this use case. So, I
tried generating a graph with relations using core.logic
(defn ->maps
>
> "take the output of run* and convert it into sequence of maps"
> [q]
> (let [r (->> q
> (partition 2)
> (map (fn [[k v]] {k (apply vector v)}))
> (apply merge))]
> r ))
> (defn gen-hierarchy
> "generate a related hierarchy"
> [size]
> (let [vars1 (->> (repeatedly 7 lvar) (into []))
> vars2 (->> (repeatedly 7 lvar) (into []))
> vars3 (->> (repeatedly 7 lvar) (into []))]
> (->>
> (run size [q]
> (fresh [?k1 ?k2 ?k3 ?v1 ?v2 ?v3 ?a]
> (fd/distinct vars1)
> (everyg #(fd/in % (fd/interval 1 9)) vars1)
> (fd/in ?k1 (fd/interval 1 9))
> (rembero ?k1 vars1 ?v1)
> (membero ?k2 ?v1)
> (fd/distinct vars2)
> (everyg #(fd/in % (fd/interval 1 9)) vars2)
> (rembero ?k2 vars2 ?v2)
> (membero ?k3 ?v2)
> (fd/distinct vars3)
> (everyg #(fd/in % (fd/interval 1 9)) vars3)
> (rembero ?k3 vars3 ?v3)
> (appendo [?k1 ?v1] [?k2 ?v2] ?a)
> (appendo ?a [?k3 ?v3] q)))
> (map ->maps))))
>
>
Hooking this into test.check. I tried the following:
(defn gen-port-hierarchy []
> (gen/sized (fn [size]
> (gen/fmap #(gen-hierarchy %) (gen/return size)))))
> (gen/sample (gen/not-empty (gen-port-hierarchy)) 1)
Which does produce more or less what I'm after:
(({6 [2 3 4 5 7 1], 3 [6 7 1 2 4 5], 1 [3 2 4 5 6 7]})
({5 [1 2 3 4 6 7], 7 [5 3 4 6 1 2], 1 [7 2 3 4 5 6]}))
However, when I try use this in a spec:
(prop/for-all [bindings (gen/not-empty (gen-port-hierarchy))]
(let [ ks (into #{} (keys bindings))] ...)
I seem to be getting back a LazySeq which then leads to a
ClassCastException:
java.lang.ClassCastException: clojure.lang.PersistentArrayMap cannot be
cast to java.util.Map$Entry
Am I on the completely wrong path here?
Or have I incorrectly hooked this generator up with test.check?
Any help would be very appreciated.
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