The A/B test does not have any impact on the search engine optimization. Indeed, indexing bots (Google, Yahoo!, Bing, etc.) are automatically excluded from the A/B tests. They can only see the original page of your website, so it does not affect your SEO nor the results of your A/B test.
<link rel="canonical" href="http://www.mywebsite.com/my-page">
Simply replace the URL of the exemple by the URL of the original page of your test.
For further information about this tag, please refer to Google support and the article on how to use canonical URLs.