You're now ready to test the package. This involves unzipping and uploading the theme to a WordPress installation, which mirrors a live environment where it will be used.

Ideally, you'll want to install your theme on a web server installation, preferably the one where the theme is going to be used (if it's a custom design for a single client), or under the circumstances you feel your theme's users are most likely to use (for example, if you're going to post your theme for download on the WordPress theme repository, then test your theme on an installation of WordPress on a shared hosting environment which most people use).

Don't assume that the ZIP file you made is going to unzip or unpack properly (files have been known to be corrupt).