fix demunge, add test

add cljs.js/file->ns

Author: swannodette

src/main/cljs/cljs/core.cljs

@@ -9898,7 +9898,8 @@ Maps become Objects. Arbitrary keys are encoded to by key->js."
 (defn- demunge-str [munged-name]
   (let [r (js/RegExp. (demunge-pattern) "g")
         munged-name (if (gstring/endsWith munged-name "$")
-                      (.substring munged-name 0 (dec (. munged-name -length))))]
+                      (.substring munged-name 0 (dec (. munged-name -length)))
+                      munged-name)]
     (loop [ret "" last-match-end 0]
       (if-let [match (.exec r munged-name)]
         (let [[x] match]

src/main/cljs/cljs/js.cljs

@@ -32,6 +32,12 @@
   [ns-sym]
   (string/replace (ana/munge-path ns-sym) \. \/))
 
+(defn file->ns
+  [file]
+  (let [lib-name (subs (string/replace file "/" ".")
+                   0 (- (count file) 5))]
+    (symbol (demunge lib-name))))
+
 (defn atom? [x]
   (instance? Atom x))
 

src/test/cljs/cljs/core_test.cljs

@@ -2875,6 +2875,10 @@
               arguments)))
          [])))
 
+(deftest test-munge-demunge
+  (is (= 'cljs.core/first?
+         (demunge (munge 'cljs.core/first?)))))
+
 (comment
   ;; ObjMap
   ;; (let [ks (map (partial str "foo") (range 500))