Masahiro NAKASHIMA

The theme can be changed and displayed to only logged in users.
The visitors of the website see your old theme while you are testing the new one.
Only the administrator of the WordPress site sees the new theme that can now be tested safely.
You can also use this plugin instead of “Theme Test Drive” plugin.

WP Theme Test

I have xdebug installed. There are two big Notices.

Threw two big PHP notices

The theme can be changed and displayed to only logged in users.

Create child themes from any non-child theme with the click of a button.
This plugin is multisite compatible; if used on a multisite network, controls for creating child themes will be in the network admin instead of the regular site admin. Pick the parent theme from the dropdown and name name your new child theme. You can also change the author name and select files you want to copy from the parent to the new theme.
Click the button and you’re all set!

Child Themify

Create child themes with the click of a button.

WP Theme Test vs Child Themify