CLJS-2780: Async tests prematurely terminate in Node

While the current implementation of -tear-down in the Node REPL allows
any pending (Node termination delaying) processing to finish, it
doesn't allow for any further communication between the REPL and the
Node process: It immediately destroys the Node-side socket while also
discarding any REPL-side communication structures.

This patch moves the code that discards REPL-side communication
structures to occur after awaiting Node process termination so that any
messages that are sent can be displayed. It also replaces the Node-side
destroy call to an unref: This allows any lingering communication to
occur, without causing the socket to keep the Node process alive.

Author: mfikes

src/main/clojure/cljs/repl/node.clj

@@ -240,17 +240,17 @@
     (load-javascript this provides url))
   (-tear-down [this]
     (swap! state update :listeners dec)
-    (let [tname (thread-name)]
-      (.remove results tname)
-      (.remove outs tname)
-      (.remove errs tname))
     (locking lock
       (when (zero? (:listeners @state))
         (let [sock @socket]
           (when-not (.isClosed (:socket sock))
             (write (:out sock) ":cljs/quit")
             (while (alive? @proc) (Thread/sleep 50))
-            (close-socket sock)))))))
+            (close-socket sock)))))
+    (let [tname (thread-name)]
+      (.remove results tname)
+      (.remove outs tname)
+      (.remove errs tname))))
 
 (defn repl-env* [options]
   (let [{:keys [host port path debug-port]}

src/main/clojure/cljs/repl/node_repl.js

@@ -66,7 +66,7 @@ var server = net.createServer(function (socket) {
 
                 if(":cljs/quit" == data) {
                     server.close();
-                    socket.destroy();
+                    socket.unref();
                     return;
                 } else {
                     try {

src/test/cljs_cli/cljs_cli/test.clj

@@ -115,3 +115,12 @@
           "-e" "(require 'left-pad)"
           "-e" "(left-pad 3 10 0)")
       (output-is "nil\n\"0000000003\""))))
+
+(deftest test-cljs-2780
+  (with-repl-env-filter #{"node" "nashorn"}
+    (-> (cljs-main
+          "-e" "(do (js/setTimeout #(prn :end) 500) nil)"
+          "-e" ":begin")
+      (output-is
+        :begin
+        :end))))