Unit Testing with Game Center?

is it possible to write unit tests that involve game center authentication and match methods? this would help a great deal with debugging. or do i need a mock window/view of some kind for authenticateHandler to trigger?

class GameCenterTests: XCTestCase {
    override func setUp() {
        super.setUp()
        GKLocalPlayer.local.authenticateHandler = { viewController, error in
            ...
        }
    }

    func test_EndTurn() {
        GKTurnBasedMatch.load(withID:id) { gkTurnBasedMatch, error in
            ...
        }
    }
}