Do you get a developer to test the TFS 2015 migration?

They should follow these steps:

1. Start Visual Studio 2013
2. Open Team Explorer and connect to the new TFS Server
3. Confirm that they can:

• Source Code - Browse the projects and code using the Source Code Explorer
• Source Code Operations - Get Latest on a file, make a change and check in
• Source Code History - View the history of a number of files in different projects
• Work Items - Browse and view recent work items

1. Open Visual Studio 2015 and repeat steps 1 to 3.
2. Test that your builds complete successfully on the upgraded build controller(s) and agent(s).
3. Check that they can create a new Team Project in Visual Studio 2015

Congratulations! You've completed a successful migration!