If these variables need to be set for every account, the simpler would be to add the export statements to /etc/profile. This file is not root's profile but a file sourced for every account using an interactive Bourne shell family shell (sh, ksh, bash, ...)
You can then just add at the end of this file.
export ORACLE_HOME=/oracle/product/11.1.0/db_1/
export ORACLE_SID=orcl
export TESTFOLDER_DIR=/test/testfolder/bin/
Otherwise, just add these three lines in your shell startup file (likely one of $HOME/.profile or $HOME/.bash_profile).
If you are logging in as root (which is not a good practice), that would be /.profile or /root/.profile
Finally, should you want to unconditionally set these variables whatever the shell is used and even for non interactive login stuff, like services, and if you do run Solaris 11.3 or older, you can use the /etc/default/init file. Note that the export builtin is not required in this file as it is not a real shell script but really a configuration file, eg:
ORACLE_HOME=/oracle/product/11.1.0/db_1/
ORACLE_SID=orcl
TESTFOLDER_DIR=/test/testfolder/bin/
Solaris 11.4 no more uses /etc/default/init to set environment variables to its services and instead uses svc:/system/environment:init properties:
# svccfg -s svc:/system/environment:init setprop environment/ORACLE_HOME = astring: /oracle/product/11.1.0/db_1/
# svccfg -s svc:/system/environment:init setprop environment/ORACLE_SID = astring: orcl
# svccfg -s svc:/system/environment:init setprop environment/TESTFOLDER_DIR = astring: /test/testfolder/bin/
# svcadm refresh svc:/system/environment