public void BorderLocationsTest()
        {
            /*
             * 01234567890
             * 0
             * 1 XxxX
             * 2 x  x
             * 3 x  x
             * 4 x  x
             * 5 XxxX
             * 6
             *
             */
            int xmin   = 1;
            int ymin   = 1;
            int xmax   = 4;
            int ymax   = 4;
            var answer = Calculate.BorderLocations(new Rectangle(new Coord(xmin, ymin), new Coord(xmax, ymax)));

            for (int i = 0; i < 10; i++)
            {
                for (int j = 0; j < 10; j++)
                {
                    Coord c = new Coord(i, j);
                    if (
                        i == xmin && (j == ymin || j == ymax) ||
                        j == ymin && (i == xmin || i == xmax) ||
                        i == xmax && (j == ymin || j == ymax) ||
                        j == ymax && (i == xmin || i == xmax))
                    {
                        Assert.Contains(c, answer);
                    }
                }
            }

            Assert.AreEqual(12, answer.Count);
        }