How do I A/B test in a Flow?
There are two ways you can A/B test within a flow. The first is to create a variation of an individual flow message. Once you've created your variation, you can test things like subject line or email content (only test one area per A/B test). The second way to A/B test a flow is by using a conditional split to test 2 different flow branches. There is a conditional split option for a random sample that allows you to split traffic based on a percentage down each path. 50% for example, would send 50% of your total recipients down the yes path and the remainder would travel down the no path. You can use this reference document for more specifics, examples and best practices.