Update

I've since uploaded a patch to the TfsTeam quick response sample to also include functionality to convert a Group to a Team.

With TFS 2010 it was already a common practice to create security groups as subgroups of the Contributors group to define teams. When you upgrade a Team Project Collection with such a setup to 2012, there is no way to convert these existing semi-teams to fully supported 2012 teams out of the box.

It turns out that you only need to apply a few small changes to the security group to have it upgraded.

Connect to TFS and retrieve the group:


collection = TfsTeamProjectCollectionFactory.GetTeamProjectCollection(new Uri(collectionUri));
collection.EnsureAuthenticated();
var identityManagementService = collection.GetService&ltIIdentityManagementService2&gt();
var securityIdentity = identityManagementService.ReadIdentity(group);

Set the team property and save it:


securityIdentity.SetProperty(IdentityPropertyScope.Local, "Microsoft.TeamFoundation.Team", (object) true);
identityManagementService.UpdateExtendedProperties(securityIdentity);

I'll probably end up submitting this as another patch to the TFS Team Tools project.