public void FillEfficiently(int expectedMs, int w, int h)
{
var x = 1;
var y = h / 2;
var canvas = new Canvas((w, h), 16);
var cmd = new Fill(canvas);
var op = cmd.CreateOperation();
var obstacles = new Point(1, 1).To((w - 2, h - 2))
.Concat(new Point(w - 2, 1).To((1, h - 2)))
.ToArray();
obstacles.ForEach(o => canvas.Plot(new Cell
{
Pos = o,
Brush = ConsoleColor.Green
}));
canvas.SelectedColor = ConsoleColor.Red;
canvas.CurrentPos = (x, y);
var before = DateTime.Now;
op.Execute();
var after = DateTime.Now;
True(canvas.Cells.Where(c => !obstacles.Contains(c.Pos)).All(c => c.Brush.Background == ConsoleColor.Red));
True(canvas.Cells.Where(c => obstacles.Contains(c.Pos)).All(c => c.Brush.Background == ConsoleColor.Green));
var durationMs = (after - before).TotalMilliseconds;
True(durationMs < expectedMs, $"Took milliseconds: {durationMs}");
}