public virtual void PixelXToTileXTest()
 {
     foreach (int tileSize in TILE_SIZES)
     {
         for (sbyte zoomLevel = ZOOM_LEVEL_MIN; zoomLevel <= ZOOM_LEVEL_MAX; ++zoomLevel)
         {
             Assert.AreEqual(0, MercatorProjection.PixelXToTileX(0, zoomLevel, tileSize));
             Assert.AreEqual(0, MercatorProjection.PixelXToTileX(0, MercatorProjection.ZoomLevelToScaleFactor(zoomLevel), tileSize));
         }
     }
 }