对包含HttpContext.Current.Cache的代码进行单元测试
假设我们如下代码调用了HttpContext.Current.Cache
public class CacheManager
{
public static HttpContext mHttpContext = HttpContext.Current;
public void SetCache
(string key, T value)
{
mHttpContext.Cache.Insert(key, value, null, DateTime.MaxValue, new TimeSpan(0, 100, 0));
}
public T GetCache
(string key) { return (T)mHttpContext.Cache.Get(key); } }
现在我有一个类调用了上面的GetCache<T>
public class LanguageController
{
private CacheManager cacheManger = new CacheManager();
public string Get_UserLanguage()
{
string userLanguage=cacheManger.GetCache
("userLanguage");
if (!string.IsNullOrEmpty(userLanguage)) return userLanguage;
return "zh-CN";
}
}
我们现在需要测LanguageController的Get_UserLanuage,写如下代码
[TestMethod]
public void Test_Get_UserLanguage()
{
CacheManager cacheManger = new CacheManager();
cacheManger.SetCache
("userLanguage", "en-GB");
LanguageController languageController = new LanguageController();
Assert.AreEqual(languageController.Get_UserLanguage(), "en-GB");
}
运行测试，失败，得到如下消息
System.NullReferenceException: Object reference not set to an instance of an object.
跟踪调试，发现下面方法这句mHttpContext.Cache为空
public void SetCache(string key, T value) { mHttpContext.Cache.Insert(key, value, null, DateTime.MaxValue, new TimeSpan(0, 100, 0)); }
现在，将测试代码改为如下：
[TestMethod]
public void Test_Get_Language_By_Fake()
{
HttpContext.Current = new HttpContext(new HttpRequest(null,
"http://10.10.50.127/RGV2/devtest1", null), new HttpResponse(null));
CacheManager.mHttpContext = HttpContext.Current;
CacheManager cacheManger = new CacheManager();
cacheManger.SetCache
("userLanguage", "en-GB");
LanguageController languageController = new LanguageController();
Assert.AreEqual(languageController.Get_UserLanguage(), "en-GB");
}
测试通过：
总结，当我们测试的包含HttpContext.Current.Cache代码时：
1. 将HttpContext.Current.Cache 公布为类的静态属性，这样测试时，一个地方改了，全部就改过来了
2. 用下面的代码来给HttpContext.Current赋值
HttpContext.Current = new HttpContext(new HttpRequest(null,
"http://10.10.50.127/RGV2/devtest1", null), new HttpResponse(null));
CacheManager.mHttpContext = HttpContext.Current;
3. 建议所有调用HttpContext获得值的地方，尽量公布为属性，这样方便测试,比如如下的代码我们就直接赋值了,这个和本文关系不大，只是一个实践而已。
public class ConfigController
{
private string tempConfigPath;
public string mConfigPath
{
get
{
if (tempConfigPath == null)
{
tempConfigPath = HttpContext.Current.Server.MapPath(@"~/App_Data/config.xml");
}
return tempConfigPath;
}
set
{
tempConfigPath = value;
}
}
}
4. 我们也可以使用Mock，但是个人认为上面的方法更简单点。