Actually, you DO compete against other players in test levels.

"I'm at lvl 12"
"lol, I'm still at lvl 4"
"still? I'll have finished by the time you get to 5."

...get my point? That's why I play online, and for this:

"How do you do #7, it's so hard"
"The thing on the right isn't a warp"
"Oh, thanks"

And I play because they're FUN, not to improve my skills. What's the point of competing anyway? So you can say "I'm probably the best player in this game. hehe"

Or, you can say: "Woop! I beat this test level!"