In order to test provisioning of resources to a user via OneRoster, you can now temporarily override the information sent by ClassLink to any OneRoster-enabled resource.
In the CMC, go to Groups & Users->Users, find the user whose information you wish to override, and click the green "Override OneRoster data" button under Action.
On the window that pops up, you can see the user's details, which include their sourcedId, username, display name, and email address. Only the user's sourcedId can be changed.
On the next window you can set orgs for the user to be associated with. To see what orgs they are currently assigned to (if any, click the "Assigned Only" box.
Next, you can set classes for the user to be assigned to. As with orgs, clicking the "Assigned Only" box will show what classes the user is already assigned to (if any)