The theme check plugin is an easy way to test your theme and make sure it's up to spec with the latest theme review standards. With it, you can run all the same automated testing tools on your theme that WordPress.org uses for theme submissions.
See the readme.txt for the full plugin description.
wp theme review check <theme-name>
This version of Theme Check adds a WP-CLI command to wp theme, to perform the theme check at the command line.
wp theme review list
You can also list the themes, which shows the display name and folder name for each theme in the site. The check command expects the folder name, so this is helpful to grab the correct name.
With this version of Theme Check, you can also use my grunt task, wp_theme_check to automate testing your theme as you build.