clojure.spec regression bug for 1.9.0-alpha6

[Alan Thompson]

Hi - Just noticed that the :ret function in fdef seems to be ignored in 1.9.0-alpha6:

user=> (require '[clojure.spec :as s])
user=> (defn dummy [x] (if x "yes" "no"))
user=> (s/fdef dummy
  #_=>   :args (s/cat :x integer?)
  #_=>   :ret  integer?)
user=> (s/instrument #'dummy)
user=> (dummy 3) (println *clojure-version*)
ExceptionInfo Call to #'user/dummy did not conform to spec:
val: "yes" fails at: [:ret] predicate: integer?
:clojure.spec/args  (3)
  clojure.core/ex-info (core.clj:4703)
{:major 1, :minor 9, :incremental 0, :qualifier alpha5}

;-------------------------------------------------------------------

user=> (dummy 3) (println *clojure-version*)
"yes"
{:major 1, :minor 9, :incremental 0, :qualifier alpha6}

[Alex Miller]

As noted in the alpha change list, this was an intentional change in what instrument does. Instrument is intended to be used to verify that other callers have invoked a function correctly. Checking that the function works (by verifying that :ret and :fn return valid results) should be done using one of the spec.test functions during testing.

Some other spec features are still to be added as well that relate to this change.

[webber]

Maybe, the following is the same reason.

```
(defn ranged-rand   ;; BROKEN!

  "Returns random integer in range start <= rand < end"

  [start end]

  (+ start (rand-int (- start end))))

(s/fdef ranged-rand

  :args (s/and (s/cat :start integer? :end integer?)

               #(< (:start %) (:end %)))

  :ret integer?

  :fn (s/and #(>= (:ret %) (-> % :args :start))

             #(< (:ret %) (-> % :args :end))))

(ranged-rand 8 10)

;;=> ExceptionInfo Call to #'spec-example.core/ranged-rand did not conform to spec:

;;=> At: [:fn] val: {:args {:start 8, :end 10}, :ret 7} fails predicate: (>= (:ret %) (-> % :args :start))

;;=> :clojure.spec/args  (8 10)

;;=>   clojure.core/ex-info (core.clj:4617)

(println *clojure-version*)

;;=> {:major 1, :minor 9, :incremental 0, :qualifier alpha1}

(s/instrument #'ranged-rand)

(ranged-rand 8 10)

;;=> 7

(println *clojure-version*)

;;=> {:major 1, :minor 9, :incremental 0, :qualifier alpha6}

```

[Alex Miller]

I'm in the process of updating that part of the guide right now, should be done by end of day.

[Sean Corfield]

Given that we now have to use clojure.spec.test to get :ret / :fn tested, we lose the “nice” exceptions explaining the conformance failure:

 

Alpha 5:

 

;;=> ExceptionInfo Call to #'spec-example.core/ranged-rand did not conform to spec:

;;=> At: [:fn] val: {:args {:start 8, :end 10}, :ret 7} fails predicate: (>= (:ret %) (-> % :args :start))

;;=> :clojure.spec/args  (8 10)

;;=>   clojure.core/ex-info (core.clj:4617)

 

Alpha 6:

 

boot.user=> (t/check-var #'ranged-rand)

{:result {:clojure.spec/problems {[] {:pred (>= (:ret %) (-> % :args :start)), :val {:args {:start -1, :end 2}, :ret -2}, :via [], :in []}}, :failed-on :fn}, :seed 1466016600676, :failing-size 4, :num-tests 5, :fail [(-1 2)], :shrunk {:total-nodes-visited 5, :depth 1, :result {:clojure.spec/problems {[] {:pred (>= (:ret %) (-> % :args :start)), :val {:args {:start -1, :end 1}, :ret -2}, :via [], :in []}}, :failed-on :fn}, :smallest [(-1 1)]}}

 

Are there plans to provide an “explain” equivalent for this?

 

Sean Corfield -- (904) 302-SEAN
An Architect's View -- http://corfield.org/

"If you're not annoying somebody, you're not really alive."
-- Margaret Atwood

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[Alex Miller]

You haven't pretty-printed it to look very nice, but I think all of the same information (and more due to shrinking) is still in the check-var output. I don't know of any plan to add what you're asking for beyond what's below.

{:result

 {:clojure.spec/problems

  {[]

   {:pred (>= (:ret %) (-> % :args :start)),

    :val {:args {:start -1, :end 2}, :ret -2},

    :via [],

    :in []}},

  :failed-on :fn},

 :seed 1466016600676,

 :failing-size 4,

 :num-tests 5,

 :fail [(-1 2)],

 :shrunk

 {:total-nodes-visited 5,

  :depth 1,

  :result

  {:clojure.spec/problems

   {[]

    {:pred (>= (:ret %) (-> % :args :start)),

     :val {:args {:start -1, :end 1}, :ret -2},

     :via [],

     :in []}},

   :failed-on :fn},

  :smallest [(-1 1)]}}

[Sean Corfield]

I fear you’re missing my point.

 

You can get close to the previous nice value with:

 

(#’s/explain-out (:result (t/check-var  #’ranged-rand)))

 

But that leverages a private function / implementation detail and doesn’t handle :failed-on very nicely:

 

boot.user=> (#'s/explain-out (:result (t/check-var #'ranged-rand)))

val: {:args {:start -3, :end 1}, :ret -5} fails predicate: (>= (:ret %) (-> % :args :start))

:failed-on  :fn

 

When you run-all-tests you get the non-pretty-printed version as a hard-to-read blob of text on stdout and a bare pass/fail map result. Having that text formatted via something like explain-out would be a big help for usability when testing. Having that function exposed publicly would be a nice convenience for other tooling to build on top of clojure.spec.test.

 

We can pass :reporter-fn to check-var / check-fn, but we run-all-tests just passes println in and calls (prn ret) on the result of check-var so we have no control over that output.

 

Sean Corfield -- (904) 302-SEAN
An Architect's View -- http://corfield.org/

"If you're not annoying somebody, you're not really alive."
-- Margaret Atwood

 

--

[Alex Miller]

explain-out is now public in master. Further mods may be coming re testing.

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[Nikita Prokopov]

How to I make spec/fdef and regular clojure.test (not generative ones) work together? I’d like for my :ret specs and HOF :ret specs to be checked during regular tests. Is that possible?

[Alex Miller]

There is nothing provided or planned to do that.