svoid test_bwContrastQuadtree_minOfArea(BWImage img) {
  BWContrastQuadTree qt = bwImageContrastQuadtree(img);
  repeat 10000 {
    ping();
    Rect r = randomRect(imageRect(img));
    int min1 = bwImage_minOfArea(img, r);
    int min2 = bwContrastQuadtree_minOfArea(qt, img.getWidth(), r);
    assertEqualsVerbose(str(r), min1, min2);
  }
}