@Test
public void testAdd() throws Exception {

    assertEquals("afarm", spelling.addCharAt("farm", 0, 'a'));
    assertEquals("faarm", spelling.addCharAt("farm", 1, 'a'));
    assertEquals("faarm", spelling.addCharAt("farm", 2, 'a'));
    assertEquals("faram", spelling.addCharAt("farm", 3, 'a'));
    assertEquals("farma", spelling.addCharAt("farm", 4, 'a'));
}