NUnit FileNotFoundException: System.Configuration

Question

I want to run some acceptance tests using Watin and I get the following error when i try to open the test assembly in NUnit GUI:

System.IO.FileNotFoundException: Could not load file or assembly 'System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

Exception details:

System.IO.FileNotFoundException...

Server stack trace: 
   at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.UnitySerializationHolder.GetRealObject(StreamingContext context)
   at System.Runtime.Serialization.ObjectManager.ResolveObjectReference(ObjectHolder holder)
   at System.Runtime.Serialization.ObjectManager.DoFixups()
   at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, IMethodCallMessage methodCallMessage)
   at System.Runtime.Remoting.Channels.BinaryClientFormatterSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at NUnit.Core.TestRunner.Load(TestPackage package)
   at NUnit.Core.ProxyTestRunner.Load(TestPackage package)
   at NUnit.Util.ProcessRunner.Load(TestPackage package)
   at NUnit.Util.TestLoader.LoadTest(String testName)

Everything worked just fine before I added a reference to System.Configuration in order to read the base url from the App.config

Answer 1

It appears that the problem was the order of sections in the App.config file.

I first added the appSettings section first, but after I moved it down everything started working as it should again.

Here's the App.config content:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
        <sectionGroup name="NUnit">
            <section name="TestRunner" type="System.Configuration.NameValueSectionHandler"/>
        </sectionGroup>
    </configSections>

    <NUnit>
        <TestRunner>
            <add key="ApartmentState" value="STA"/>
        </TestRunner>
    </NUnit>

    <appSettings>
        <add key="BaseUrl" value="http://localhost/Test"/>
    </appSettings>
</configuration>