Just curious if there is any form of testing to detect PCOS? ?

Is there any kind of test to detect PCOS? My doctor told me back in September I had PCOS but didn't do any kind of testing,just told me to do the keto diet. 

I have heard yes there are test to detect PCOS and and I also heard there isn't,but ever since I have been taking vitamin d vitamins. My cycles are becoming regular. I'm just thinking if my cycles are regular now since the vitamin d vitamins are helping. 

I have read lack of vitamin d is lacking of many health conditions. Don't know how true it is!

Does the keto diet treat PCOS at all?