svoid test_pixelSpiral() {
  for (int w = 1; w <= 5; w++)
    for (int h = 1; h <= 5; h++) {
      print("Testing " + w + "*" + h);
      Set<Pt> allPoints = asSet(allPointsInRect(w, h));

      for x to w: for y to h: {
        L<Pt> l = asList(pixelSpiral(1, 1, 3, 3));
        assertEquals(l(l), w*h);
        assertEquals(asSet(l), allPoints);
        assertEquals(First(l), pt(x, y));
        // We trust ther remaining points are in the correct order
      }
    }
}