js: improve connection check

--

* Connection.js: In some cases, the browser disconnect does not
  happen inmediately (e.g. wrong extension for the app). I added a
  delay of 25 ms to see if the connection was closed by the browser.
  Also, I tried to make the checkConnection more readable.

lang/js/BrowserTestExtension/tests/startup.js

@@ -44,4 +44,16 @@ describe('GPGME context', function (){
                 done();
             });
     });
+
+    it('Error message on unsuccessful connection (timeout)', function (done) {
+        let prm = Gpgmejs.init({ timeout: 1 });
+        prm.then(
+            null,
+            function (error){
+                expect(error).to.be.an('error');
+                expect(error.code).to.equal('CONN_TIMEOUT');
+                done();
+            }
+        );
+    });
 });

lang/js/src/Connection.js

@@ -99,25 +99,29 @@ export class Connection{
             timeout = 1000;
         }
         const msg = createMessage('version');
-        if (details === true) {
-            return this.post(msg);
-        } else {
-            let me = this;
-            return new Promise(function (resolve) {
-                Promise.race([
-                    me.post(msg),
+        const prm = Promise.race([
+            this.post(msg),
             new Promise(function (resolve, reject){
                 setTimeout(function (){
                     reject(gpgme_error('CONN_TIMEOUT'));
                 }, timeout);
             })
-                ]).then(function (){ // success
+        ]);
+        return new Promise( function (resolve, reject) {
+            prm.then(function (success){
+                if (details === true ) {
+                    resolve(success);
+                } else {
                     resolve(true);
-                }, function (){ // failure
-                    resolve(false);
-                });
-            });
                 }
+            }, function (error) {
+                if (details === true ) {
+                    reject(error);
+                } else {
+                    resolve(false);
+                }
+            });
+        });
     }
 
     /**
@@ -141,14 +145,6 @@ export class Connection{
             this.disconnect();
             return Promise.reject(gpgme_error('MSG_INCOMPLETE'));
         }
-        if (this.isDisconnected) {
-            if ( this.isNativeHostUnknown === true) {
-                return Promise.reject(gpgme_error('CONN_NO_CONFIG'));
-            } else {
-                return Promise.reject(gpgme_error(
-                    'CONN_NO_CONNECT', this._connectionError));
-            }
-        }
         let chunksize = message.chunksize;
         const me = this;
         const nativeCommunication = new Promise(function (resolve, reject){
@@ -185,6 +181,20 @@ export class Connection{
             };
             me._connection.onMessage.addListener(listener);
             me._connection.postMessage(message.message);
+
+            // check for browser messaging errors after a while
+            // (browsers' extension permission checks take some time)
+            setTimeout( () => {
+                if (me.isDisconnected) {
+                    if ( me.isNativeHostUnknown === true) {
+                        return reject(gpgme_error('CONN_NO_CONFIG'));
+                    } else {
+                        return reject(gpgme_error(
+                            'CONN_NO_CONNECT', me._connectionError));
+                    }
+                }
+            }, 25);
+
         });
         if (permittedOperations[message.operation].pinentry === true) {
             return nativeCommunication;
@@ -193,7 +203,7 @@ export class Connection{
                 nativeCommunication,
                 new Promise(function (resolve, reject){
                     setTimeout(function (){
-                        me._connection.disconnect();
+                        me.disconnect();
                         reject(gpgme_error('CONN_TIMEOUT'));
                     }, 5000);
                 })