When rel canonical tag used, which page does Google considers for ranking and indexing? A/B test scenario!

[vtmoz]

Hi Moz community,

We have redesigned our website and launched for A/B testing using canonical tags from old website to new website pages, so there will be no duplicate content issues and new website will be shown to the half of the website visitors successfully to calculate the metrics. However I wonder how actually Google considers it? Which pages Google will crawl and index to consider for ranking? Please share your views on this for better optimisation.

Thanks