SQL> create user test identified by 1;

User created.

SQL> grant connect to test;

Grant succeeded.

SQL> conn test/1
ERROR:
ORA-01017: invalid username/password; logon denied


Warning: You are no longer connected to ORACLE.
SQL>

SQL>
SQL> conn sys as sysdba
Enter password:
Connected.
SQL>

SQLNET.AUTHENTICATION_SERVICES= (NTS)

NAMES.DIRECTORY_PATH= (TNSNAMES, ONAMES, HOSTNAME)

SQL> drop user test cascade;

User dropped.

SQL> create user test identified by "a";

User created.

SQL> grant connect to test;

Grant succeeded.

SQL> conn test/"a"
ERROR:
ORA-01017: invalid username/password; logon denied


Warning: You are no longer connected to ORACLE.
SQL> conn test/a
ERROR:
ORA-01017: invalid username/password; logon denied


SQL> conn test/A
ERROR:
ORA-01017: invalid username/password; logon denied


SQL> conn test/"A"
ERROR:
ORA-01017: invalid username/password; logon denied

connect system/manager 
--      or any other account with CREATE USER privilege or DBA role but NOT SYS
create user test identified by "a";
grant connect to test;
conn test/"a"