@Override
  public boolean isAction() {
    if (expression != null) {
      return expression.isAction();
    }
    return false;
  }
@Test
  public void isAction() {
    when(expr.isAction()).thenReturn(true).thenReturn(false);
    assertTrue(test.isAction());
    assertFalse(test.isAction());
    verify(expr, times(2)).isAction();
    verifyNoMoreInteractions(expr);
  }