@Test
public void testCapitalizeFirstLetter() {

    assertNull(Tools.capitalizeFirstLetter(null));
    assertEquals("Monkey", Tools.capitalizeFirstLetter("monkey"));
    assertEquals("Kou", Tools.capitalizeFirstLetter("kou"));
    assertEquals("Up", Tools.capitalizeFirstLetter("up"));
    assertEquals("O", Tools.capitalizeFirstLetter("o"));
    assertEquals("-", Tools.capitalizeFirstLetter("-"));
    assertEquals("", Tools.capitalizeFirstLetter(""));
    assertEquals("CAKE", Tools.capitalizeFirstLetter("CAKE"));
    assertEquals("123", Tools.capitalizeFirstLetter("123"));
}