def test_merge_overlapping_coverage(self):
        color1 = (255, 255, 0)
        color2 = (0, 255, 255)
        merger = LayerMerger()
        merger.add(ImageSource(Image.new('RGB', (10, 10), color1)), self.coverage1)
        merger.add(ImageSource(Image.new('RGB', (10, 10), color2)), self.coverage2)

        result = merger.merge(image_opts=ImageOptions(), bbox=(0, 0, 10, 10), bbox_srs=3857)
        img = result.as_image()
        eq_(img.mode, 'RGB')

        expected = create_image((10, 10), color1, 'RGB')
        draw = ImageDraw.Draw(expected)
        draw.polygon([(2, 2), (7, 2), (7, 7), (2, 7)], fill=color2)

        for x in range(0, 9):
            for y in range(0, 9):
                eq_(img.getpixel((x, y)), expected.getpixel((x, y)))

 def test_outside(self):
     sub_img = create_image((50, 50), color=[100, 120, 130, 140])
     img = SubImageSource(sub_img, size=(100, 100), offset=(200, 0), image_opts=ImageOptions(transparent=True)).as_image()
     eq_(img.getcolors(), [(100*100, (255, 255, 255, 0))])

 def test_overlap_right(self):
     sub_img = create_image((50, 50), color=[100, 120, 130, 140])
     img = SubImageSource(sub_img, size=(100, 100), offset=(75, 25), image_opts=ImageOptions(transparent=True)).as_image()
     eq_(sorted(img.getcolors()), [(25*50, (100, 120, 130, 140)), (100*100-25*50, (255, 255, 255, 0))])

 def test_negative_offset(self):
     sub_img = create_image((150, 150), color=[100, 120, 130, 140])
     img = SubImageSource(sub_img, size=(100, 100), offset=(-50, 0), image_opts=ImageOptions()).as_image()
     eq_(img.getcolors(), [(100*100, (100, 120, 130, 140))])