The first major wave of that testing, a closed beta, is going down January 24 to January 29 and the development team has revealed the specific times that it will run. Information on downloading the beta client can be found on the game's FAQ.
This controller is a limited edition and you can get it on February 15th, 2018.
Featuring a "translucent design" and "laser-etched barnacles", the controller also has its own hidden treasure in the form of one single golden trigger (it's the right trigger, if you're wondering) as well as a nautical design on the rear of the controller.
What content will be available in the Sea of Thieves Closed Beta?
If you pre-ordered Sea of Thieves digitally from the Xbox Store, the beta will automatically appear in your game library 24 hours before it begins.
The closed beta will be a "bespoke" experience according to Rare and it will give players a taste of the pirate action ahead of the launch. Also, the beta will not be under NDA, meaning players can "stream, create videos, share clips, take screenshots", and more, without worrying about the giant foot of Microsoft coming down on them, which is more than welcome.