Complete local bindings for ClojureScript files

When editing a ClojureScript file, cider-nrepl doesn't offer any local
binding names (the function name and argument names if inside the
function, the let-like block bindings if inside a let-like block,
etc.) as completion candidates, like it does when editing a Clojure
file.

The root of the problem is that
`cider.nrepl.middleware.complete/cljs-sources` only includes
`::suitable-sources/cljs-source` as a possible source. And `suitable`
doesn't perform any local binding analysis.

Given that the local binding analysis done in
`compliment.sources.local-bindings` namespace doesn't perform any
evaluation or execution of the context form (thus, it is independent
of the actual host platform differences), we can use that same source
for ClojureScript local bindings completion.

[Closes: #766]

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### New features
+
+* [#766](https://github.com/clojure-emacs/cider-nrepl/issues/766) Complete local bindings for ClojureScript files.
+
 ## 0.29.0 (2022-12-05)
 
 ### New features

src/cider/nrepl/middleware/complete.clj

@@ -36,7 +36,13 @@
 
 (def cljs-sources
   "A list of ClojureScript completion sources for compliment."
-  [::suitable-sources/cljs-source])
+  [::suitable-sources/cljs-source
+   ;; The local binding analysis done by
+   ;; :compliment.sources.local-bindings/local-bindings doesn't perform any
+   ;; evaluation or execution of the context form. Thus, it is independent of
+   ;; the actual host platform differences. Given that, we can use that same
+   ;; source for ClojureScript completion.
+   :compliment.sources.local-bindings/local-bindings])
 
 (defn complete
   [{:keys [ns prefix symbol context extra-metadata enhanced-cljs-completion?] :as msg}]

test/cljs/cider/nrepl/middleware/cljs_complete_test.clj

@@ -64,7 +64,18 @@
                                      :ns "cljs.user"
                                      :prefix "js/Ob"})
           candidates (:completions response)]
-      (is (empty? candidates)))))
+      (is (empty? candidates))))
+  (testing "local bindings"
+    (let [response (session/message {:op "complete"
+                                     :ns "cljs.user"
+                                     :prefix "ba"
+                                     ;; Including `quux :quux` helps ensuring that only
+                                     ;; bindings with the specified prefix (ba*) will be
+                                     ;; suggested, instead of all the local bindings.
+                                     :context "(defn foo [bar] (let [baz :baz, quux :quux] (str __prefix__)))"
+                                     :enhanced-cljs-completion? "t"})
+          candidates (:completions response)]
+      (is (= [{:candidate "bar", :type "local"}, {:candidate "baz", :type "local"}] candidates)))))
 
 (deftest cljs-complete-doc-test
   (testing "no suitable documentation can be found"