The short version: Create a clean MySQL database and user. DO NOT USE AN EXISTING DATABASE or you will lose data, guaranteed. Copy wp-tests-config-sample.php to wp-tests-config.php, edit it and include your database name/user/password. $ svn up Run the tests from the "trunk" directory: To execute a particular test: $ phpunit tests/test_case.php To execute all tests: $ phpunit Notes: Test cases liv