'test with colors set to a 4d float array of rgb data'

@image_comparison(baseline_images=['voxels-rgb-data'], extensions=['png'], remove_text=True)
def test_rgb_data(self):

    (fig, ax) = plt.subplots(subplot_kw={'projection': '3d'})
    (x, y, z) = np.indices((10, 10, 10))
    voxels = ((x == y) | (y == z))
    colors = np.zeros((10, 10, 10, 3))
    colors[..., 0] = (x / 9.0)
    colors[..., 1] = (y / 9.0)
    colors[..., 2] = (z / 9.0)
    ax.voxels(voxels, facecolors=colors)
