Loading .config files in NUnit

Last week I gave a presentation at Microsoft DevDays 2004 in Lisbon on Test-Driven Development. A day later I got this interesting question:

"(...) if I'm testing a DLL assembly that uses a .config file to read in data, when I run the tests, NUnit loads it's own .config file and all my tests fail. How can I solve this ?"

I also had this same problem a while back. There are two separate answers to this question as far as I could tell:

  1. If we're using the NUnit GUI than it's just a question to specify which .config file to load (Project -> Edit)

  2. If we're running NUnit from the console, copy the config file to the directory where the test assembly is located (tipically bin\Debug) and rename the config file to <test assembly>.config (ex: UniTests.dll.config)

This will cause NUnit to load the required .config file.

Comments (8)
  1. One other interesting thing I have found with nunit is that if you are testing multiple assemblies utilizing the .nunit project file, you can add all of your configuration information in to a file called .nunit.config and it will then load the configuration information from that file for the tests.

  2. I have also created .nunit files and run them from the command line. This makes it easy to use the same nunit file in an automated build process. re : http://blog.iceglue.com/archive/2004/05/12/168.aspx

  3. Hans Sissing (J.J.Sissing@[nospam]hetnet.nl says:

    If I enable VS support, hence I can load a csproj file instead of the assembly, then my app fails to find the config file, even if I configured it through "Project | Edit".

    Which config file is read?


  4. José Almeida says:

    With VS Support enabled you also have to specify the config file in the NUnit GUI (Project -> Edit). Place the .config file in the same dir as the assembly, set the Application Base to the same directory and specify the .config filename correctly. That should do the trick.

  5. Hans Sissing (J.J.Sissing@[nospam]hetnet.nl says:

    That’s what I did, but it does not seem to load the config file or look in the right directory.

    If I load the assembly, it works, if I load the project it refues to load the config, and I put a config file in almost every directory that possible could be read, and named the file in al it’s variations:




  6. Hans Sissing (J.J.Sissing@[nospam]hetnet.nl says:

    Ok, if found out which config file is loaded if you enable VS.NET support and load your project instead of the assembly.

    Query the following property in your code:


    The result is: "d:appsmyprojmyproj.csproj.config".

    And yes, copying "d:appsmyprojbindegugmyproj.dll.config" to the above location and name does the trick.

    Hence, there is some bug in NUnit that does not set the ConfigurationFile property to a value you would expect…

  7. José Almeida says:

    Glad you managed to solve your problem, though I have to admit I wasn’t able to repro it. With my setup everything just worked by specifying the application base and correct .config filename in the NUnit GUI.

    Thanks for posting your findings. 🙂

  8. Mike Lorengo says:

    Just to reiterate what Hans said,

    I too had a problem with NUnit 2.2 reading my config files. I was using a .nunit project file. I queried the value of

    AppDomain.CurrentDomain.SetupInformation.ConfigurationFile =


    So in my case myproj reads myproj.nunit.config in the binDebug folder

    So, if you’re having a problem query the value in your test assembly

    Thanks Hans!

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