Checking Roles of a user in oracle.

From SYS (To see all the privileges sys can provide to a user):

select * from role_sys_privs; 

From DBA user: 

select * from dba_role_privs where grantee='USER';

From the user itself:

select * from user_role_privs;

Miscellaneous:

SELECT * FROM DBA_TAB_PRIVS where owner='USER1' and grantee like'TEST_USER%';

SELECT * FROM ALL_TAB_PRIVS where grantee like'USER';