A/B Split Test For Wordpress

We manage our websites with Wordpress. Recently, we started searching for split test plugins and tools but couldn't find something that supports the following requirements:

1. Test the same post with changes in the Single Post (single.php) file
2. Test changes in stylesheet (stylesheet.css)
3. Test changes in themes

I would appreciate any assistant if anyone is aware of existing tools that can help.

via Chebli Mohamed