Hi there! 

It might have changed, but my most up-to-date knowledge is that it is a 45 minute quant test to ascertain your math and critical thinking skills. It's a screening test which determines whether you will move forward with the interview process. 

The best way to practice is to really find online tests / questions and practice. Regardless as to whether is a new or old test, the principles are mostly the same across these quant screening tests: 

• Time management (need to think quick)
• Business knowledge/context (incl key formulas)
• Critical thinking (answers that are very similar to each other...clues "hidden" in the text)
• Ability to interpret data/charts

Think of it as a merge of a case and the GMAT/GRE. You need to be clear on some key case-related and account formulas (margin, growth, breakeven, etc) as well as be good at critically understanding the question (including nuance to questions) and parsing through complicated text with a fair amount of distraction. You'll also need to be good at chart/graph reading. The (old) McKinsey PST, BCG Online Test, Bain SOVA test, etc. are all quite similar so leverage resources across all of them.