Ansible role: test/test.yml

Hi,

When initiating a role I noticed that there is a test folder being created with test.yml in it. When I run my roles in production environments, I always run roles by creating a playbook with the following contents:

`

---
- hosts: webservers
  roles:
     - common
     - webservers

`

When running this playbook, the role gets executed. But what is the difference with running the test.yml file? Is it not necessary that I create my own playbook at the parent directory that the folder with the role is also in?