Test levels has a good gameplay, there's wroth in join them.
If you not are such much good in battle, a test is great, I do better like test levels than battle levels, sinice it's total fair in test levels, but in battle, it's about who's oldest and have most skills.
Test levels is good also becuse you get more challenge in the 'who complete first', where the newbies is an enemy too, a better one than in battle.
There's nothing wrong with test levels, I really like puzzles and test levels, they always have a decent good gameplay.
When you finish a hard test level, you also feel better, and even you won't say it, you get more happy, becuse you'r good