Frequent socketexception in nUnit GUI

[Ivar Yrke]

Windows 7 64 bit, VS2010 .Net 4.0, nUnit 2.5.10

I like to use nUnit GUI with the options automatic reload and automatic rerun last tests. This works fine for a while (anything from a few times to quite a few times) but then ends up in an error message stating

Title: "Assembly Not Loaded"
Text: "System.NetSockets.SocketException : An existing connection was forcibly closed by the remote host"

If I try to reload the project I get the same error once more. This is consistent with my impression that the error first occurs on a automatically triggered reload.
If I try to run the test after this message I get a NullReferenceException.

The only way out is to close nUnit and restart.
This error is quite annoying and disrupting to my attemp to work test driven.

[Charlie Poole (charlie.poole)]

Please provide the stack trace that is available from the last exception dialog.

[Ivar Yrke (iyrke)]

Below is stack trace from the NullReferenceException.

As you can imaging it was not so easy to get this error when I wanted to provoke it. That led me to do something that might be a clue to the problem. I ended up adjusting and recompiling my unit test very quickly, basically before nUnit completed running the tests on the prevous build. Then I got the error. And it appears I could also repeat the error easily doing that.

Stack trace:
System.NullReferenceException: Object reference not set to an instance of an object.
   at NUnit.Core.ProxyTestRunner.BeginRun(EventListener listener, ITestFilter filter)
   at NUnit.Util.TestLoader.RunTests(ITestFilter filter)
   at NUnit.UiKit.TestSuiteTreeView.RunTests(ITest[] tests, Boolean ignoreCategories)
   at NUnit.UiKit.TestSuiteTreeView.RunSelectedTests()
   at NUnit.UiKit.TestTree.RunSelectedTests()
   at NUnit.Gui.NUnitForm.runButton_Click(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)