Add support for auto loading services when defined as string

see issue #18

Application.js

@@ -134,13 +134,17 @@ class Application extends Service {
             let
               serviceDefinition = servicesConfig[serviceKey];
 
-            if (typeof serviceDefinition === 'function') {
+            if (typeof serviceDefinition === 'function' || typeof serviceDefinition === 'string') {
                 serviceDefinition = {
                     service: serviceDefinition
                 };
             }
 
-            if (serviceDefinition !== null && typeof serviceDefinition.service === 'function') {
+            if (serviceDefinition !== null && serviceDefinition.service) {
+                if (typeof serviceDefinition.service === 'string') {
+                    serviceDefinition.service = this._loadService(serviceDefinition.service);
+                }
+
                 // instantiate the fetched service class.
                 let service = new (serviceDefinition.service)(serviceManager);
                 serviceManager.set(serviceKey, service);
@@ -192,6 +196,17 @@ class Application extends Service {
 
         return this;
     }
+
+    /**
+     * Load and return a service by its path.
+     *
+     * @param servicePath
+     * @returns {*}
+     * @private
+     */
+    _loadService(servicePath) {
+        return require(servicePath);
+    }
 }
 
 module.exports = Application;

test/Application.js

@@ -309,4 +309,27 @@ describe('kermit::application', function() {
           'Expect service `test2` to be configured with no config through the service definition configKey property that equals `null`.'
         );
     });
+
+    it('should load services if defined as string.', function() {
+        var app = new Application;
+
+        app.configure({
+            configs: [{
+                app: {
+                    services: {
+                        test: __dirname + '/lib/Service',
+                        test2: __dirname + '/../Service'
+                    }
+                }
+            }]
+        }).bootstrap().launch();
+
+        assert(
+            app.getServiceManager().has('test')
+        );
+
+        assert(
+            app.getServiceManager().has('test2')
+        );
+    });
 });

test/lib/Service.js

@@ -0,0 +1,14 @@
+/**
+ * kermit - soa infrastructure for node js
+ *
+ * @copyright   Copyright (c) 2015, Alrik Zachert
+ * @license     https://gitlab.com/kermit-js/kermit/blob/master/LICENSE BSD-2-Clause
+ */
+
+"use strict";
+
+const BaseService = require('../../Service');
+
+class Service extends BaseService {}
+
+module.exports = Service;