How can I automatically restore my site from a backup using the command line for testing purposes? I am on Mac OS X using MAMP PRO as my local development environment.  I want to quickly reset my site to a known state in order to run some tests I have prepared in Selenium.

I have the Backup and Migrate module installed which makes it easy to restore from the command line via drush, but if I restore using Backup and Migrate it appears to only overwrite the existing data and leaves other data in place, which I don't want-- I want to erase all of this other data as well so that I can be sure that the database is in exactly the same state as the backup file.

Currently, I log in to PHPmyadmin, drop all of the tables in the database, and then re-import from the backup.  This seems somewhat inefficient to me; is there a way to automate this from the command line?
I use /applications/mamp/library/bin/mysqldump -uUSERNAME -pPASSWORD DATABASE &gt;backup.sql to back my database up and then /applications/mamp/library/bin/mysql -uUSERNAME -pPASSWORD DATABASE &lt;backup.sql to restore it.