模拟一个私人领域 [英] Mocking a private field

问题描述

我知道有人问过类似的问题，但我没有找到明确的解决方案.我正在尝试从一个大类中模拟一个私有字段.私有字段是通过一些较早的方法实例化的，我正在尝试对引用该字段的后一种方法进行单元测试.

I know a similar question has been asked but I have not found a clear solution. I'm trying to mock a private field from a large class. The private field gets instantiated in some earlier method and I'm trying to unit test a latter method which references the field.

所以我的课堂上有一个更早的方法:

So I have an earlier method in my class:

public bool validateAll(ref DataEntry[] oEntries, string sMediaPlanId, ITemplateGenerator oTempGen)
{
  ...
  // private field that I am trying to mock
  this._sMediaPlanObjective = (MPWrapper.Instance).getMediaPlanObjective(sMediaPlanId);
  ...
}

我正在尝试对引用私有字段的方法进行单元测试:

And I'm trying to Unit test a method that references the private field:

public bool validateFlightObjective(ref MPDataEntry oEntry)
{
  ...
  string entryFlightObjective = oEntry.getFlightObjective();
  string mediaPlanObjective = this._sMediaPlanObjective;

  if (entryFlightObjective != mediaPlanObjective)
  {
    return false;
  }
  ...

  return true;      
}

鉴于我有一个很大的类，而这只是我要测试的一种方法，有没有一种方法可以模拟这个私有字段?我是缺少基本的东西还是应该考虑其他方法?

Given that I have a large class and this is just one method I want to test, is there a possible way to just mock this private field? Am I missing something basic or should I consider some other approach?

推荐答案

您不能模拟任何私有，静态或本质上不可替代的 (这是免费的模拟库限制).

You can't mock anything that's private, static, or essentially - non overridable (this comes as a free mocking libraries limitation).

在这种情况下(当private成员已被进行测试时)，您通常要做的是将private成员提取到一个单独的类中，并

What you usually do in such situations (when it appears that private member has to be tested), is extracting your private member to a separate class and inject it to tested class as a dependency.

在您的情况下，您实际上需要提取创建_sMediaPlanObjective的代码，这是以下行:

In your case, you actually need to extract code that creates _sMediaPlanObjective, which is this line:

this._sMediaPlanObjective =
    (MPWrapper.Instance).getMediaPlanObjective(sMediaPlanId);

提供getMediaPlanObjective方法的

对象应注入到测试的类中.如果这样做，您可以简单地模拟该对象，并告诉它返回模拟的_sMediaPlanObjective版本.

Object that provides getMediaPlanObjective method should be injected to your tested class. If you do so, you can simply mock that object and tell it to return mocked version of _sMediaPlanObjective.

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