|Sex||A lot with her sister|
|Occupation||Drug dealer and self-proclaimed scientist|
|Relatives||Johnny Test (brother) Mary Test (twin sister and girlfriend) Hugh Test (father) Lila Test (mother)|
|Introduced in||The Great Meatloaf-Off|
|Latest appearance||The Latest Episode|
|Voiced by||Maryke Hendrikse|
Susan Test is the sister of Johnny Test, the twin sister of Mary Test, and the daughter of Hugh Test and Lila Test. She is also a lesbian and a chain smoker, as revealed in Adam's Hot Scoop! Secrets Revealed?.
Susan Test is a nerd who, like her sister, pretty much gets horny everytime she even hears the word 'science'. She and Mary are normally are busy in the garage (or "the lab" as they call it) making meth all day to make a profit (and sometimes just to see Johnny on meth for shits and giggles). They both idolize Walter White from Breaking Bad almost as much as they idolize Gil Nexdor. Despite being a lesbian chain smoker, she still lusts after Gil because he's virtually a chick anyway. She is always the victim of Bling-Bling Bitch's kidnapping schemes, but she always manages to escape mostly thanks to The Big Four (and particularly Johnny). She develops drugs with her sister to use on Bling-Bling Bitch so they can knock him out and feed him to monkeys.
- According to the episodes The Prom and Adam's Hot Scoop! Secrets Revealed, Susan's username on Rainbow Instapic is Les_chainsmoke_4evr.
- She might not actually be a lesbian chain smoker however, and may just be lying so that Bling-Bling Bitch will lose interest in her.