How to test sub-domains on my localhost on a mac?

Must be adding to the file /etc/hosts:

127.0.0.1       localhost blog.localhost lvh.me blog.lvh.me

Example for Vim editor (small overview about working in Vim)

1. Run to edit file /etc/hosts:

    sudo vi /etc/hosts
   

2. In Vim press on keyboard button i to switch on edit mode

3. Add this line:

    127.0.0.1       localhost blog.localhost lvh.me blog.lvh.me
   

4. Save file:

• Press button Esc and after press together buttons shift :

• Now you will see line in which write x and press Enter

Thats all, localhost, blog.localhost, lvh.me and blog.lvh.me are already available for all ports that you are using.

Edit the file /etc/hosts, add the following line:

127.0.0.1 example.com blog.example.com

Then try http://example.com:8000/ and http://blog.example.com:8000/