add tests for default service config

* verify default service config is applied properly
* verify config is merged properly into the default config

see issue #11

test/Service.js

@@ -10,6 +10,7 @@ const
     Config = require('../Config'),
     Service = require('../Service'),
     ServiceManager = require('../ServiceManager'),
+    ServiceWithDefaultConfig = require('./lib/ServiceWithDefaultConfig'),
     EventEmitter = require('events').EventEmitter;
 
 describe('srvoa::service', function() {
@@ -96,4 +97,30 @@ describe('srvoa::service', function() {
 
         assert(srv.serviceConfig.get('test.test2') === undefined, 'Expected config key `test.test2` to equal undefined after resetting configuration.');
     });
+
+    it('should apply the default service config during configuration.', function() {
+        var srv = new ServiceWithDefaultConfig();
+
+        assert(srv.serviceConfig === null, 'Expected `serviceConfig` to be null before configure is called.');
+
+        srv.configure();
+
+        assert(srv.serviceConfig instanceof Config, 'Expected `serviceConfig` to be instance of `Config` after configure is called.');
+        assert(srv.serviceConfig.get('test.test2') === 1, 'Expected default service config to be applied thus config key `test.test2` must equal 1.');
+    });
+
+    it('should merge config into default service config during configuration.', function() {
+        var srv = new ServiceWithDefaultConfig();
+
+        srv.configure({
+            test: {
+                test2: 2
+            },
+            test2: 1
+        });
+
+        assert(srv.serviceConfig.get('test.test2') === 2, 'Expected configs got merged properly thus config key `test.test2` must equal 2.');
+        assert(srv.serviceConfig.get('test.test3') === 1, 'Expected configs got merged properly thus config key `test.test3` must equal 1.');
+        assert(srv.serviceConfig.get('test2') === 1, 'Expected configs got merged properly thus config key `test2` must equal 1.');
+    });
 });

test/lib/ServiceWithDefaultConfig.js

@@ -0,0 +1,16 @@
+"use strict";
+
+const Service = require('../../Service');
+
+class ServiceWithDefaultConfig extends Service {
+  getDefaultServiceConfig() {
+    return {
+      test: {
+        test2: 1,
+        test3: 1
+      }
+    };
+  }
+}
+
+module.exports = ServiceWithDefaultConfig;