Fixed gulp test rule: chdir to build to test

Related: simcaq/SCRUM#68

gulpfile.babel.js

@@ -59,6 +59,7 @@ gulp.task('doc', (cb) => {
 });
 
 gulp.task('test', ['build'], () => {
+    process.chdir('build');
     gulp.src('test/test.js', {read: false})
     .pipe(mocha())
     .once('error', () => {

src/test/test.js

@@ -12,7 +12,9 @@ const expect = chai.expect;
 
 const should = chai.should(); // actually call the function
 
-const server = require('../libs/app');
+const libs = `${process.cwd()}/libs`;
+
+const server = require(`${libs}/app`);
 
 chai.use(chaiHttp);