MySQL error 1045(28000): Access denied for user ...

Problem

I have a database called hibernate in my MySQL server and I grant privileges to a user using this command
    > grant all on hibernate.* to 'testuser'@'%' identified by 'testuser';
Wildchar % means no matter where the user logs in mysql server from, the access should be allowed for further checking/verification.
When I tried to log in as the newly created user from local host, I got this error:
    ERROR 1045 (28000): Access denied for user 'testuser'@'localhost' (using password: YES)
Also I tried some suggested solutions:
   > FLUSH PRIVILEGES:
   > SET PASSWORD FOR 'testuser'@'%'='testuser';
None of them works.

My solution:
Using following two commands:
   > grant all on hibernate.* to 'testuser'@'%' identified by 'testuser';
   > grant all on hibernate.* to 'testuser'@'localhost' identified by 'testuser';

Theoretically, wildchar % should have included all hosts. But it may not cover localhost. Who knows