Spamassassin comes with sample-spam.txt and sample-nonspam.txt - guess what these are?

Send them to yourself and make sure spamassassin picks them up as spam / ham.
You will see
some spam as SA is not 100% effective. You can get a head-start by running sa-learn against all of your current ham and spam (if you keep your spam).
Dennis
Ps: if you've not already done so, configure SA to use 'spamc' rather than 'spamassassin'. Piping spam to a daemonised SA uses far fewer resources than calling SA for every mail.