Hi all,
Without having looked at the test.check internals, I'm trying to figure
out roughly what kind of generator function, the following spec will give:
(s/def ::predicate (s/fspec :args (s/cat :x any?)
:ret boolean?))
So, I'm trying to sort of reverse engineer it on the repl:
(def p (second (first (s/exercise ::predicate 1))))
=> #'specs.encore/p
p
=>
#object[clojure.spec$fspec_impl$reify__14282$fn__14285
0x5cb07a8d
"clojure.spec$fspec_impl$reify__14282$fn__14285@5cb07a8d"]
(p 1)
=> false
(p [])
=> false
*(p :a)**
**=> true *
(p :b)
=> false
*(p :a)**
**=> true*
*(p :a)**
**=> false*
Ok, so the predicate returned does not always return the same boolean
value (so not constructed via `constantly`). But it also returns a
different boolean, given the same argument (so not a real predicate in
the sense that it looks at the argument and then decides)! Only one
option remains, as far as I can see...`p` seems to return true or false
randomly. Can anyone confirm this?
If my understanding is correct, how would one write the :fn spec of a
function like `clojure.core/remove`? Wouldn't it make sense to try to
verify that the :ret collection does NOT contain any elements satisfying
the predicate used? Similarly for `clojure.core/filter`. A reasonable
:fn spec for it should try to confirm that ALL elements in :ret satisfy
that predicate used, right? But if the predicate generated returns
true/false randomly, one cannot reliably use it under the :fn spec.
Unless, I'm missing something of course...Thanks in advance :)
Kind regards,
Dimitris
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