export and import metadata without changing data of imported database.

Hi. I have a production and test database running oracle10. db details are as follows.

SQL> select * from v$version;

BANNER

----------------------------------------------------------------

Oracle Database 10g Release 10.2.0.4.0 - 64bit Production

PL/SQL Release 10.2.0.4.0 - Production

CORE    10.2.0.4.0      Production

TNS for Solaris: Version 10.2.0.4.0 - Production

NLSRTL Version 10.2.0.4.0 - Production

Some of the procedures,functions,packages in test database  are changed by users .

So for testing purposes ,it is difficult to validate with the production database.

Now they want to restore those objects such as procedures,functions,packages from production_db to test_db without changing the data exists in test_db.

Since it is a large database, how can I export and import those objects (metadata) without changing data in the target db(test_db).