To be fair 90% of US systems/platforms are not battle tested either. The wars America has had in last few decades are against third world militaries or outfits like Taliban. The only thing tested in these wars is US infantry, light weapons, logistics etc.
How exactly has US Navy been tested in any of these wars? Indeed even USAF has not really been tested. Even then experiance and tested can only go so far. There was a time in early part of the last century when the most tested military was German. But it lost out against the numbers and greater industrial capacity of it's foes. Indeed US and Russia mostly copied German technology after WW2. The wheel does not always need reinventing.
As Chinese R&D surges and their industrial capacity reaches 3/4 times USA expect PLAN to support a fleet larger then USN and as if not more advanced. It's only matter of time. Maybe another four decades. There was a time when Royal Navy was dominant. Then greater US industrial productivity translated into USN gaining ascendancy. Around the corner PLAN is shaping up.