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为WPF项目创建单元测试

时间:2010-10-29 00:04来源:知行网www.zhixing123.cn 编辑:麦田守望者

可能你已发现一个问题,我们无法使用VS对WPF项目创建单元测试(VS2005不行,VS2008我没试过,但据说也不行),这让人很郁闷,这里将介绍如何使用NUnit来对WPF项目创建单元测试并解决其中的难题(但利用NUnit来对WPF创建单元测试时并不会像针对.Net2.0一样容易,可能会出现一些小问题).

1,对普通类(非WPF UI组件)进行测试:
这和在.Net2.0中使用NUnit进行测试时一样,不会出现任何问题,参考下面的代码:


[TestFixture]
public class ClassTest
{
[Test]
public void TestRun()
{
ClassLibrary1.Class1 obj = new ClassLibrary1.Class1();

double expected = 9;
double result = obj.GetSomeValue(3);

Assert.AreEqual(expected, result);
}
}

2,对WPF UI组件进行测试
使用NUnit对WPF UI组件(比如MyWindow,MyUserControl)进行测试的时候,NUnit会报如下异常:“The calling thread must be STA, because many UI components require this”。
下面是错误的测试代码:

[TestFixture]
public class ClassTest
{
[Test]
public void TestRun()
{
WindowsApplication1.Window1 obj = new WindowsApplication1.Window1();

double expected = 9;
double result = obj.GetSomeValue(3);

Assert.AreEqual(expected, result);
}
}

 

为了让调用线程为STA,我们可以编写一个辅助类CrossThreadTestRunner:

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Security.Permissions;
using System.Reflection;

namespace TestUnit
{
public class CrossThreadTestRunner
{
private Exception lastException;

public void RunInMTA(ThreadStart userDelegate)
{
Run(userDelegate, ApartmentState.MTA);
}

public void RunInSTA(ThreadStart userDelegate)
{
Run(userDelegate, ApartmentState.STA);
}

private void Run(ThreadStart userDelegate, ApartmentState apartmentState)
{
lastException = null;

Thread thread = new Thread(
delegate()
{
try
{
userDelegate.Invoke();
}
catch (Exception e)
{
lastException = e;
}
});
thread.SetApartmentState(apartmentState);

thread.Start();
thread.Join();

if (ExceptionWasThrown())
ThrowExceptionPreservingStack(lastException);
}

private bool ExceptionWasThrown()
{
return lastException != null;
}

[ReflectionPermission(SecurityAction.Demand)]
private static void ThrowExceptionPreservingStack(Exception exception)
{
FieldInfo remoteStackTraceString = typeof(Exception).GetField(
"_remoteStackTraceString",
BindingFlags.Instance | BindingFlags.NonPublic);
remoteStackTraceString.SetValue(exception, exception.StackTrace + Environment.NewLine);
throw exception;
}
}
}
并编写正确的测试代码:

[TestFixture]
public class ClassTest
{
[Test]
public void TestRun()
{

CrossThreadTestRunner runner = new CrossThreadTestRunner();
runner.RunInSTA(
delegate
{
Console.WriteLine(Thread.CurrentThread.GetApartmentState());

WindowsApplication1.Window1 obj = new WindowsApplication1.Window1();

double expected = 9;
double result = obj.GetSomeValue(3);
Assert.AreEqual(expected, result);
});

}
}

 


另外,使用NUnit时,您需要添加对nunit.framework.dll的引用,并对测试类添加[TestFixture]属性标记以及对测试方法添加[Test]属性标记,然后将生成的程序集用nunit.exe打开就可以了,关于NUnit的具体用法您可以参考其官方文档

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