软件测试中含有HttpContext元素的单元测试
单元测试是在软件开发过程中要进行的最低级别的测试活动，在单元测试活动中，软件的独立单元将在与程序的其他部分相隔离的情况下进行测试。 单元测试不仅仅是作为无错编码一种辅助手段在一次性的开发过程中使用，单元测试必须是可重复的，无论是在软件修改，或是移植到新的运行环境的过程中。因此，所有的测试都必须在整个软件系统的生命周期中进行维护。
我们在开发WEB项目的时候，一般应用逻辑跟ASPX页面是分离的项目。应用逻辑一般会是一个DLL组件项目。如果这个组件项目中A方法使用了Session、Cookie等信息的读写，则这个方法就很难写单元测试。
但并不是写不出来，要写出来大致思路如下：
目标：
构建一个测试的环境，把需要的Session、Cookie等信息初始化好。 这样才好做测试。而且这个构建的环境，不应该影响实际功能代码的编写。
具体实现来说：
我们要使用Mock技术，但就HttpContext来言，直接mock这个对象会有一个问题，它不具备Session的功能。这时候我们就需要用 Mock 技术来构造一个可以满足我们需要的环境的原理：这个Mock的机制如下：
用反射机制，构造一个 HttpSessionState 对象（HttpSessionState类的构造函数是internal 的），然后把这个对象跟SimpleWorkerRequest 对象捆绑。
这样我们就可以 构建了一个满足自己需要的环境了，即 TestHttpContext 类。
以下是两个类的实现：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.SessionState;
using System.Web;
using System.Threading;
using System.Globalization;
using System.Collections.Specialized;
using System.Collections;
using System.IO;
using System.Web.Hosting;
using System.Reflection;
namespace TestNamespace
{
public class TestHttpContext
{
private const string ContextKeyAspSession = "AspSession";
private HttpContext context = null;
private TestHttpContext() : base() { }
public TestHttpContext(bool isSecure)
: this()
{
MySessionState myState = new MySessionState(Guid.NewGuid().ToString("N"),
new SessionStateItemCollection(), new HttpStaticObjectsCollection(),
5, true, HttpCookieMode.UseUri, SessionStateMode.InProc, false);
TextWriter tw = new StringWriter();
HttpWorkerRequest wr = new SimpleWorkerRequest("/webapp", "c:\\inetpub\\wwwroot\\webapp\\", "default.aspx", "", tw);
this.context = new HttpContext(wr);
HttpSessionState state = Activator.CreateInstance(
typeof(HttpSessionState),
BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.Instance | BindingFlags.CreateInstance,
null,
new object[] { myState },
CultureInfo.CurrentCulture) as HttpSessionState;
this.context.Items[ContextKeyAspSession] = state;
HttpContext.Current = this.context;
}
public HttpContext Context
{
get
{
return this.context;
}
}
private class WorkerRequest : SimpleWorkerRequest
{
private bool isSecure = false;
public WorkerRequest(string page, string query, TextWriter output, bool isSecure)
: base(page, query, output)
{
this.isSecure = isSecure;
}
public override bool IsSecure()
{
return this.isSecure;
}
}
}
public sealed class MySessionState : IHttpSessionState
{
const int MAX_TIMEOUT = 24 * 60; // Timeout cannot exceed 24 hours.
string pId;
ISessionStateItemCollection pSessionItems;
HttpStaticObjectsCollection pStaticObjects;
int pTimeout;
bool pNewSession;
HttpCookieMode pCookieMode;
SessionStateMode pMode;
bool pAbandon;
bool pIsReadonly;
public MySessionState(string id,
ISessionStateItemCollection sessionItems,
HttpStaticObjectsCollection staticObjects,
int timeout,
bool newSession,
HttpCookieMode cookieMode,
SessionStateMode mode,
bool isReadonly)
{
pId = id;
pSessionItems = sessionItems;
pStaticObjects = staticObjects;
pTimeout = timeout;
pNewSession = newSession;
pCookieMode = cookieMode;
pMode = mode;
pIsReadonly = isReadonly;
}
public int Timeout
{
get { return pTimeout; }
set
{
if (value <= 0)
throw new ArgumentException("Timeout value must be greater than zero.");
if (value > MAX_TIMEOUT)
throw new ArgumentException("Timout cannot be greater than " + MAX_TIMEOUT.ToString());
pTimeout = value;
}
}
public string SessionID
{
get { return pId; }
}
public bool IsNewSession
{
get { return pNewSession; }
}
public SessionStateMode Mode
{
get { return pMode; }
}
public bool IsCookieless
{
get { return CookieMode == HttpCookieMode.UseUri; }
}
public HttpCookieMode CookieMode
{
get { return pCookieMode; }
}
//
// Abandon marks the session as abandoned. The IsAbandoned property is used by the
// session state module to perform the abandon work during the ReleaseRequestState event.
//
public void Abandon()
{
pAbandon = true;
}
public bool IsAbandoned
{
get { return pAbandon; }
}
//
// Session.LCID exists only to support legacy ASP compatibility. ASP.NET developers should use
// Page.LCID instead.
//
public int LCID
{
get { return Thread.CurrentThread.CurrentCulture.LCID; }
set { Thread.CurrentThread.CurrentCulture = CultureInfo.ReadOnly(new CultureInfo(value)); }
}
//
// Session.CodePage exists only to support legacy ASP compatibility. ASP.NET developers should use
// Response.ContentEncoding instead.
//
public int CodePage
{
get
{
if (HttpContext.Current != null)
return HttpContext.Current.Response.ContentEncoding.CodePage;
else
return Encoding.Default.CodePage;
}
set
{
if (HttpContext.Current != null)
HttpContext.Current.Response.ContentEncoding = Encoding.GetEncoding(value);
}
}
public HttpStaticObjectsCollection StaticObjects
{
get { return pStaticObjects; }
}
public object this[string name]
{
get { return pSessionItems[name]; }
set { pSessionItems[name] = value; }
}
public object this[int index]
{
get { return pSessionItems[index]; }
set { pSessionItems[index] = value; }
}
public void Add(string name, object value)
{
pSessionItems[name] = value;
}
public void Remove(string name)
{
pSessionItems.Remove(name);
}
public void RemoveAt(int index)
{
pSessionItems.RemoveAt(index);
}
public void Clear()
{
pSessionItems.Clear();
}
public void RemoveAll()
{
Clear();
}
public int Count
{
get { return pSessionItems.Count; }
}
public NameObjectCollectionBase.KeysCollection Keys
{
get { return pSessionItems.Keys; }
}
public IEnumerator GetEnumerator()
{
return pSessionItems.GetEnumerator();
}
public void CopyTo(Array items, int index)
{
foreach (object o in items)
items.SetValue(o, index++);
}
public object SyncRoot
{
get { return this; }
}
public bool IsReadOnly
{
get { return pIsReadonly; }
}
public bool IsSynchronized
{
get { return false; }
}
}
}
这样我们在进行单元测试时就可以Mock掉Web下的Session,Cookie等对象。
例如：
[TestMethod()]
public void TestGetUserId()
{
TestHttpContext mock = new TestHttpContext(false);
System.Web.HttpContext context = mock.Context;
context.Session["UserId"] = 1245;
Assert.AreEqual(long.Parse(context.Session["UserId"].ToString()), 1245, "读取用户ID错误！");
}
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