@Test
    public void testNextImage() {
        ValidationCode vc = new ValidationCode();
        RenderedImage image = vc.nextImage(11111111, true);
        try {
            ImageIO.write(image, "PNG", new File("d:\\test\\test.png")); 
        } catch(Exception e) {
            
        }
        String str= vc.getValidationCode();
        assertThat(str.length(), is(4));
    }