public void Should_ClearPositions() { // setup IBoardState state = ModelLocator.BoardState; var positions = new[] { ChessPosition.A2, ChessPosition.A1, ChessPosition.A4, ChessPosition.E3 }; foreach (var position in positions) { state.Add(position); } // execute state.Clear(); // verify Assert.IsTrue(positions.All(p => !state.Contains(p))); }