Mockito when().thenReturn不必要地调用该方法

Question

我正在研究一个继承的代码.我写了一个应该捕获NullPointerException的测试(因为它试图从null对象调用一个方法)

@Test(expected=NullPointerException.class)
public void checkXRequirement_NullProduct_AddAction_ShouldThrowNullPointerException() throws CustomException {
  Site site = mock(Site.class);
  Product product = null;
  when(BasketHelper.getAction(request)).thenReturn(0);
  when(BasketHelper.getActionProduct(site, request)).thenReturn(product);
  BasketHelper.requiresX(request, site);

}

相关方法和变量:

public static final int ACTION_ADD = 0;
public static final int ACTION_DELETE = 1;

protected static int getAction(HttpServletRequest a_request) {
  String sBuyProduct = a_request.getParameter(ATTRIBUTE_NAME_BUY_PRODUCT);
  String sBuyProduct = a_request.getParameter(ATTRIBUTE_NAME_BUY_PRODUCT);

  if (sBuyProduct != null) iAction = ACTION_ADD;
  else (sDelProduct != null) iAction = ACTION_DELETE;

  return iBasketAction
}

protected static Product getActionProduct(Site a_site, HttpServletRequest a_request) {

    String sBuyProduct = a_request.getParameter(ATTRIBUTE_NAME_BUY_PRODUCT);
    String sDelProduct = a_request.getParameter(ATTRIBUTE_NAME_DEL_PRODUCT);
    String sProduct = null;

    switch (getBasketAction(a_request)) {
        case BASKET_ACTION_ADD:
        sProduct = sBuyProduct;
    break;
        case BASKET_ACTION_DELETE:
        sProduct = sDelProduct;
    break;
    }

    int iProductId;
    try {
        iProductId = Integer.parseInt(sProduct);
    } catch (NumberFormatException nbrEx) {
        return null;
    }

    Product prod = getProductById(iProductId);

    if (prod.isMasterProduct()) {
        prod = getChildProduct(prod, a_site, a_request);
    }

    return prod;
}


public static boolean requiresX(HttpServletRequest request, Site site) throws CustomException {
  try{
    if (getAction(request) == ACTION_ADD) { 
    Product prod = getActionProduct(site, request);
    return prod.getType().isRequiredX();
    }  
  } catch(NullPointerException exception) {
    log.error("Error Message", exception);
  }
  return false;
}

运行测试的jUnit结果是堆栈跟踪失败:

java.lang.Exception: Unexpected exception, expected<java.lang.NullPointerException> but was<org.mockito.exceptions.misusing.WrongTypeOfReturnValue>
Caused by: org.mockito.exceptions.misusing.WrongTypeOfReturnValue: 
Integer cannot be returned by getParameter()
getParameter() should return String#

我是否误解了何时().thenReturn应该在这里工作？我只是希望getAction返回0并且getActionProduct在被调用时返回null.很明显,getParameter()被调用,我不知道为什么.

Answer 1

Mockito不能模拟静态方法.您的检查无效时:

  when(BasketHelper.getAction(request)).thenReturn(0);
  when(BasketHelper.getActionProduct(site, request)).thenReturn(product);

这是我们想要减少静态方法使用的另一个原因,因为它很难模拟.

如果您的班级保持这样,就没有更简单的方法来模仿行为.但是,如果您想要更改设计并使两种方法都是非静态的.使用"when"的正确方法是对mocked对象应用检查.例如:

  BasketHelper basketHelper = mock(BasketHelper.class);
  when(basketHelper.getAction(request)).thenReturn(0);
  when(basketHelper.getActionProduct(site, request)).thenReturn(product);

但是,如果您将类的getAction和getProduct方法重新设计为NON-STATIC,这只会再次起作用.

我记得有一些其他测试框架支持模拟静态方法.