Nunit 2.6 无法调试.Net Framework 4.0

<configuration>
  <!--
   The GUI only runs under .NET 2.0 or higher. The
   useLegacyV2RuntimeActivationPolicy setting only
   applies under .NET 4.0 and permits use of mixed
   mode assemblies, which would otherwise not load
   correctly这里面必须去掉version 2.0 的设置
   -->
<startup useLegacyV2RuntimeActivationPolicy="true">
    <requiredRuntime version="v4.0.30319" />
    <supportedRuntime version="v4.0.30319" />
  </startup>
  <runtime>
    <!-- Ensure that test exceptions don't crash NUnit -->
    <legacyUnhandledExceptionPolicy enabled="1" />


    <!-- Run partial trust V2 assemblies in full trust under .NET 4.0 -->
    <loadFromRemoteSources enabled="true" />

    <!-- Look for addins in the addins directory for now -->
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <probing privatePath="lib;addins" />
    </assemblyBinding>
  </runtime>
</configuration>

<configuration>
  <!--
   The GUI only runs under .NET 2.0 or higher. The
   useLegacyV2RuntimeActivationPolicy setting only
   applies under .NET 4.0 and permits use of mixed 
   mode assemblies, which would otherwise not load 
   correctly这里面必须去掉version 2.0 的设置
   --> 
<startup useLegacyV2RuntimeActivationPolicy="true">
	<requiredRuntime version="v4.0.30319" />
    <supportedRuntime version="v4.0.30319" />
  </startup>
  <runtime>
    <!-- Ensure that test exceptions don't crash NUnit -->
    <legacyUnhandledExceptionPolicy enabled="1" />


    <!-- Run partial trust V2 assemblies in full trust under .NET 4.0 -->
    <loadFromRemoteSources enabled="true" />
    
    <!-- Look for addins in the addins directory for now -->
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <probing privatePath="lib;addins" />
    </assemblyBinding>
  </runtime>
</configuration>

ok，可以了，如果你想要看framework 版本号，可以直接输入%systemroot%Microsoft.NETFramework