If you are using MAMP be sure to add the unix_socket
key with a value of the path that the mysql.sock
resides in MAMP.
'mysql' => array(
'driver' => 'mysql',
'host' => 'localhost',
'unix_socket' => '/Applications/MAMP/tmp/mysql/mysql.sock',
'database' => 'database',
'username' => 'root',
'password' => 'root',
'charset' => 'utf8',
'collation' => 'utf8_unicode_ci',
'prefix' => '',
),