在单元测试创​​建的System.Web.Caching.Cache对象 [英] Creating a System.Web.Caching.Cache object in a unit test

问题描述

我想实现在一个没有单元测试项目中的功能单元测试，这功能需要的System.Web.Caching.Cache对象作为参数。我一直在尝试使用code，如...

I'm trying to implement a unit test for a function in a project that doesn't have unit tests and this function requires a System.Web.Caching.Cache object as a parameter. I've been trying to create this object by using code such as...

System.Web.Caching.Cache cache = new System.Web.Caching.Cache();
cache.Add(...);

...然后通过高速缓存作为参数，但Add（）函数导致一个NullReferenceException。我最好的猜测到目前为止，我不能在单元测试创​​建该缓存对象，并需要从我显然不具备在一个单元测试访问HttpContext.Current.Cache检索。

...and then passing the 'cache' in as a parameter but the Add() function is causing a NullReferenceException. My best guess so far is that I can't create this cache object in a unit test and need to retrieve it from the HttpContext.Current.Cache which I obviously don't have access to in a unit test.

你怎么单元测试需要的System.Web.Caching.Cache对象作为参数的函数吗？

How do you unit test a function that requires a System.Web.Caching.Cache object as a parameter?

推荐答案

当我一直面临着这样的问题（其中有问题的类没有实现一个接口），我经常写出来与包装有关类别各地相关的接口。然后，我用我的包装在我的code。单元测试，我用手模拟包装，并插入我自己的模仿对象进去。

When I've been faced with this sort of problem (where the class in question doesn't implement an interface), I often end up writing a wrapper with associated interface around the class in question. Then I use my wrapper in my code. For unit tests, I hand mock the wrapper and insert my own mock object into it.

当然，如果一个模拟框架的工作，然后用它来代替。我的经验是，所有嘲弄框架有各种.NET类的一些问题。

Of course, if a mocking framework works, then use it instead. My experience is that all mocking frameworks have some issues with various .NET classes.

public interface ICacheWrapper
{
   ...methods to support
}

public class CacheWrapper : ICacheWrapper
{
    private System.Web.Caching.Cache cache;
    public CacheWrapper( System.Web.Caching.Cache cache )
    {
        this.cache = cache;
    }

    ... implement methods using cache ...
}

public class MockCacheWrapper : ICacheWrapper
{
    private MockCache cache;
    public MockCacheWrapper( MockCache cache )
    {
        this.cache = cache;
    }

    ... implement methods using mock cache...
}

public class MockCache
{
     ... implement ways to set mock values and retrieve them...
}

[Test]
public void CachingTest()
{
    ... set up omitted...

    ICacheWrapper wrapper = new MockCacheWrapper( new MockCache() );

    CacheManager manager = new CacheManager( wrapper );

    manager.Insert(item,value);

    Assert.AreEqual( value, manager[item] );
}

皇家code

...

CacheManager manager = new CacheManager( new CacheWrapper( HttpContext.Current.Cache ));

manager.Add(item,value);

...

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