@Override
  public int getPrecedence() {
    if (expression != null) {
      return expression.getPrecedence();
    }
    return -1;
  }
@Test
  public void getPrecedence() {
    int precedence = 12345;
    when(expr.getPrecedence()).thenReturn(precedence);
    assertEquals(precedence, test.getPrecedence());
    verify(expr).getPrecedence();
    verifyNoMoreInteractions(expr);
  }