@Test
	public void validPosition(){
		Tile[][] tiles = new Tile[20][20];
		for (int x = 0; x < tiles.length; x++){
			for(int y = 0; y < tiles[0].length; y++){
				tiles[x][y] = new Tile(new Position(x, y), 0);
			}
		}
		World w = new World(tiles);
		
		
		Position p1 = new Position(-1, 1);
		assertTrue(!(w.validPosition(p1)));
		
		Position p2 = new Position(w.getWidth() + 1, 1);
		assertTrue(!(w.validPosition(p2)));
		
		Position p3 = new Position(1, -1);
		assertTrue(!(w.validPosition(p3)));
		
		Position p4 = new Position(1, w.getHeight() + 1);
		assertTrue(!(w.validPosition(p4)));
		
		
	}