Fix info op not to return nil as a document for protocl

[liquidz]

• The commits are consistent with our contribution guidelines
• You've added tests to cover your change(s)
• All tests are passing
• The new code is not generating reflection warnings
• You've updated the README (if adding/changing middleware)

Currently, the meta data for protocol method without docstring has a nil value for :doc key.

(defn foo [])
(defn bar "..." [])
(defprotocol Dummy
  (hello [this])
  (world [this] "..."))

(meta #'foo)   ; not containing `:doc`
(meta #'bar)   ; containing `:doc`
(meta #'hello) ; containing `:doc`, but nil
(meta #'world) ; containing `:doc`

The nil value is treated as a list by nrepl/bencode, so info op returns a empty list as a docstring for protocol method.
https://github.com/nrepl/bencode/blob/v1.0.0/src/bencode/core.clj#L324

E.g. info response for hello

d12:arglists-str6:[this]3:docle4:file47:file:/.../core.clj4:linei7e4:name5:hello2:ns8:foo.core8:protocol16:#'foo.core/Dummy7:session36:3b4401ac-a962-43b1-8fbc-1c17d
b0477346:statusl4:doneee

# 3:docle <= Here!

Is this an expected behavior?

This PR will dissociate :doc key when the value is nil not to return empty list as a bencode response.

[bbatsov]

Is this an expected behavior?

It is, but it's definitely not ideal as clients can't tell apart an empty list from a nil. Generally it's best to avoid returning empty keys as you suggested.

This PR will dissociate :doc key when the value is nil not to return empty list as a bencode response.

Probably we can have a more generic solution and drop any metadata that's nil from the response. Then the clients would know that if something's missing it's nil.

[liquidz]

@bbatsov Thanks! I fixed a commit.

CI for Java 11, Clojure 1.10 seems failure, but I didn't change anything about cljs-inspect-test and the CI is successful in my local environment.

$ java -version
openjdk version "11.0.2" 2019-01-15
OpenJDK Runtime Environment 18.9 (build 11.0.2+9)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.2+9, mixed mode)

$ lein with-profile +1.10,+test test cider.nrepl.middleware.cljs-inspect-test

lein test cider.nrepl.middleware.cljs-inspect-test
Warning: Nashorn engine is planned to be removed from a future JDK release

Ran 19 tests containing 50 assertions.
0 failures, 0 errors.

[bbatsov]

Looks good to me. Just mention this fix in the changelog and we're good to go.

[liquidz]

@bbatsov I just fixed changelog!
https://github.com/clojure-emacs/cider-nrepl/compare/525c0871900b18e3703f9f6e44d4d9f50bf0ff26..e4b0a131d1b3ea29714814701783876fcdc118fa

[bbatsov]

Thanks!