@Override
  public String[] getHelp() {
    if (expression != null) {
      return expression.getHelp();
    }
    return null;
  }
@Test
  public void getHelp() {
    String[] help = new String[] { "Help 1", "Help 2", "Help 3" };
    when(expr.getHelp()).thenReturn(help);
    assertArrayEquals(help, test.getHelp());
    verify(expr).getHelp();
    verifyNoMoreInteractions(expr);
  }