High School Musical cutie Vanessa Hudgens recently tested her on-and-off-screen boyfriend Zac Efron, reports Life & Style.

Egged on by her gal pals to gauge her man’s loyalty, Vanessa, 19, sent “a really hot friend” to chat him up at the gym where he works out.

“He had no idea she was a friend of Vanessa’s,” says an insider involved in the scheme. “The hottie started talking to him, but Zac didn’t flirt back — and she’s gorgeous!”

Apparently Zac, 20, passed the test!

Added the insider, “He’s only got eyes for Vanessa. And we had fun with the prank!”