public void CanAddBattleshipToPlain() { var mockPlain = new Mock <IHaveBattleships>(); var service = new BattleService(); var battleship = new Battleships.StateManager.Entities.Battleship(new Position(1, 1), new Position(2, 1)); service.AddBattleship(mockPlain.Object, battleship); mockPlain.Verify(x => x.AddBattleship(battleship), Times.Once); }