Intellij IDEA phpunit autocomplete

Step 1 : use composer install phpunit in htdocs
$ cd htdocs
$ mkdir PHPUnit
$ sudo vi composer.json

{

  "require-dev": {

    "phpunit/phpunit": "4.8.*" //PHP >=5.6 use "5.0.*"

  }

}

$ composer install

Step 2 : include External libraries in Intellij IDEA project