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:
| 以下是引用片段： [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:
| 以下是引用片段： [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:
| 以下是引用片段： 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; } } } |
