Bullet Train A/B Testing
An example of this can be ran at https://jsfiddle.net/vw0af7zq/.
How was this feature created in Bullet Train?
Step 1: Create a remote config called hero
Set the value to be the image path you want
Step 2: Create a segment with a percentage split
This will mean you can override features for 50% of your users.
Step 3: Add another segment or user override
This overrides the hero image for a particular user, the same can be done for a particular segment of users. You can always override your % split override for particular users or other segments.
Running the example
Just clone and open index.html in your preferred browser.