@Test
public void testDefaultPadding() {

    Icon icon = new ColumnControlIcon();
    IconBorder border = new IconBorder(icon, SwingConstants.WEST);
    JLabel label = new JLabel("dummy");
    label.setBorder(border);
    Insets insets = border.getBorderInsets(label);
    // internal knowledge: default padding has been 2 * 4
    assertEquals(insets.left, icon.getIconWidth() + 8);
}