@Test
public void leftTrimTest() {

    assertNull(leftTrim(null));
    assertEquals(leftTrim(""), "");
    assertEquals(leftTrim(" \t "), "");
    assertEquals(leftTrim(" 123"), "123");
    assertEquals(leftTrim("\t123"), "123");
    assertEquals(leftTrim("\n123"), "123");
    assertEquals(leftTrim("123"), "123");
    assertEquals(leftTrim(" \n  123"), "123");
    assertEquals(leftTrim("123 "), "123 ");
    assertEquals(leftTrim(" 3 123 "), "3 123 ");
}