Update test-functional.md

docs/guide-zh-CN/test-functional.md

@@ -1,11 +1,22 @@
 功能测试
 ================
 
-> Note: 这部分正在开发中。
+Functional test verifies scenarios from a user's perspective. It is similar to [acceptance test](test-acceptance.md)
+but instead of communicating via HTTP it is filling up environment such as POST and GET parameters and then executes
+application instance right from the code.
 
-- http://codeception.com/docs/05-FunctionalTests
+Functional tests are generally faster than acceptance tests and are providing detailed stack traces on failures.
+As a rule of thumb, they should be preferred unless you have a special web server setup or complex UI powered by
+JavaScript.
 
-运行基本和高级模板功能测试
-----------------------------------------------------
+Functional testing is implemented with the help of Codeception framework which has a nice documentation about it:
 
-请参阅 `apps/advanced/tests/README.md` 和 `apps/basic/tests/README.md` 提供的说明。 
+- [Codeception for Yii framework](http://codeception.com/for/yii)
+- [Codeception Functional Tests](http://codeception.com/docs/04-FunctionalTests)
+
+## Running basic and advanced template tests
+
+If you've started with advanced template, please refer to ["testing" guide](https://github.com/yiisoft/yii2-app-advanced/blob/master/docs/guide/start-testing.md)
+for more details about running tests.  
+
+If you've started with basic template, check its [README "testing" section](https://github.com/yiisoft/yii2-app-basic/blob/master/README.md#testing).