How do I run NUnit in debug mode from Visual Studio?

Question

I've recently been building a test framework for a bit of C# I've been working on. I have NUnit set up and a new project within my workspace to test the component. All works well if I load up my unit tests from Nunit (v2.4), but I've got to the point where it would be really useful to run in debug mode and set some break points.

I've tried the suggestions from several guides which all suggest changing the 'Debug' properties of the test project:

Start external program: C:\Program Files\NUnit 2.4.8\bin\nunit-console.exe
Command line arguments: /assembly: <full-path-to-solution>\TestDSP\bin\Debug\TestDSP.dll

I'm using the console version there, but have tried the calling the GUI as well. Both give me the same error when I try and start debugging:

Cannot start test project 'TestDSP' because the project does not contain any tests.

Is this because I normally load \DSP.nunit into the Nunit GUI and that's where the tests are held?

I'm beginning to think the problem may be that VS wants to run it's own test framework and that's why it's failing to find the NUnit tests?

Edit: To those asking about test fixtures, one of my .cs files in the TestDSP project looks roughly like this:

namespace Some.TestNamespace
{
    // Testing framework includes
    using NUnit.Framework;

    [TestFixture]
    public class FirFilterTest
    {
        [Test]
        public void Test01_ConstructorTest()
        {
            ...some tests...
        }
    }
}

...I'm pretty new to C# and the NUnit test framework so it's entirely possible I've missed some crucial bit of information ;-)

Final Solution: The big problem was the project I'd used. If you pick Other Languages -> Visual C# -> Test -> Test Project ...when you're choosing the project type, Visual Studio will try and use it's own testing framework as far as I can tell. You should pick a normal C# class library project instead and then the instructions in my selected answer will work.

Answer 1

I use the same technique as you are trying Jon, without the /assembly flag, i.e.

Start External Program: C:\Program Files\NUnit 2.4.8\bin\nunit.exe

Command line arguments: "<path>\bin\Debug\Quotes.Domain.Tests.dll"

Does TestDSP.dll contain all your TestFixtures?

As my test project is not the startup project in the solution, I run my tests by right-clicking on the test project and choosing Debug --> Start New Instance

Answer 2

When I need to debug my NUnit tests, I simply attach to the NUnit GUI application nunit-agent.exe using "Debug|Attach to Process" and run the tests from the GUI. Any breakpoints in my tests (or the code they're testing) are hit. Am I misunderstanding your question, or will that work for you?

Answer 3

Simply remove the line that looks like

<ProjectTypeGuids>
    {3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}
</ProjectTypeGuids>

from your project file. This line basically tells VS.Net that it's a Test project, thus the "Cannot start test project". FYI here the 1st Guid says "it's a test", the 2nd says "it's C#". For information on those Guids: http://www.mztools.com/Articles/2008/MZ2008017.aspx

Answer 4

In addition to the answer provided by @Justin here are some more details for NUnit 2.6.

Using NUnit 2.6 attach to nunit.exe or nunit-console.exe and NOT the agent. The configuration noted by @Justin is slightly different. Below is an example from nunit.exe.config (same for nunit-console.exe.config).

<startup useLegacyV2RuntimeActivationPolicy="true">
  <!-- Comment out the next line to force use of .NET 4.0 -->
  <supportedRuntime version="v2.0.50727" />  
  <supportedRuntime version="v4.0.30319" />
</startup>

For .NET 4 test project, to get break points to hit, you will have to comment out or remove the v2.0 line as the comment suggests. Once I did that I was able to debug the .NET 4.0 test project.

Answer 5

If you are using NUnit 2.4 or newer you can put the following code in your SetUpFixture class. (You can do this with older versions but you will need to do whatever equivalent that has to the SetUpFixture, or copy it in to the test itself.)

[SetUpFixture]
public class SetupFixtureClass
{
    [SetUp]
    public void StartTesting()
    {
        System.Diagnostics.Debugger.Launch();
    }
}

What Debugger.Launch() does is cause the following dialog to show up when you click Run inside NUnit.

You then choose your running instance of visual studio with your project open (the 2nd one in my screenshot) then the debugger will be attached and any breakpoints or exceptions will show up in Visual Studio.

Answer 6

In Nunit 3.0.1 (I'm using VS2013), Open from main menu > Test > Windows > Test Explorer. Then in "Test explorer", right-click the test case, you might see:

Hope this helps.

Answer 7

Install TestDriven.NET, which is a plugin for Visual Studio

From there you can right click on your unit test assembly and click Run Tests to run the whole suite, right click on a TestFixture class to run just the tests in that class, or right click on a Test method to run just that method.

You also have the option to Test With Debugger, if you need to breakpoint into your tests in debug mode.

Answer 8

Try NUnitit - a open source Visual Studio Addin for Debugging NUnit Test cases

HomePage - http://nunitit.codeplex.com/

Answer 9

Remove ProjectTypeGuids from the project file.

Answer 10

Now with pictures:

1. Run NUnit gui (Download 2.6.2 from here) then go to File -> Open Project

2. Select your test .dll from bin folder (C:\......\[SolutionFolder][ProjectFolder]\bin\Debug\xxxxTests.dll)

3. Go to Visual Studio Debug -> Attach to process (Attach to process window will open)

4. From the list scroll down and select nunit-agent.exe then click Attach

5. At this point breakpoints in your tests should turn ripe red (from hollow).

6. Click Run on Nunit Gui and you should get your breakpoint hit...

Hope this saves you some time.

Answer 11

If you are able to get the console / or GUI working, but your breakpoints are not being hit, it may be because your app is running a different .NET runtime than NUnit is. Check to see if your nunit-console.exe.config / nunit.exe.config has the runtime specified.(The configurations live in the same directory as the nunit exe's.) Specify the runtime using the startup node:

<configuration>
    <startup>
       <supportedRuntime version="4.0" />
    </startup>

Answer 12

If project path contains spaces e.g. "New Project" in path <path>\bin\Debug\New Project\Quotes.Domain.Tests.dll then enclose the Start Option --> Command Line Arguments project path in double quotes.

I spent a lot of time to figure this out.

Answer 13

Regarding what Mr. Patrick McDonald said

As my test project is not the startup project in the solution, I run my tests by right-clicking on the test project and choosing Debug --> Start New Instance

I tried to apply for my test class library but got some error regarding the path, so I tried to remove the 'Command Line Arguments', and luckily it worked well and as expected.

Answer 14

It sounds like you are trying to use the wrong library. NUnit can only start if the dll you are using contains TestFixtures.

+1 on TestDriven.Net. I've had the chance to use it a number of times. You can download the personal version for evaluations purposes according the the license at http://testdriven.net/purchase_licenses.aspx.

Answer 15

I got the same error with MSTest. I found that in the Test Output window, some of the tests had duplicate IDs and could not be loaded. I removed all duplicate tests and now I was able to run the tests when i start the project.

Answer 16

There is also an extension now "Visual NUnit" that will allow you to run the tests from within Visual studio much like the build in test framework handles. Check it out its in the extension manager.

Answer 17

Open Visual Studio ---> your Project---> Select 'Properties'---> Select 'Debug' --> Select 'Start external program' and set the path of your NUnit there(Eg: Start external program = C:\Program Files\NUnit 2.6.2\bin\nunit.exe) ---->Save

After setting this just click Debug

Answer 18

For me solution was to adapt nunit configuration file. To use nunit with 4.5-.Net framework and x64 build option, I had to add one line to startup tag (supported runtime-version).

<startup useLegacyV2RuntimeActivationPolicy="true">
        <!-- Comment out the next line to force use of .NET 4.0 -->
        <supportedRuntime version="v4.0.30319" />
</startup>

Afterwards, I could start by right-click on the Testproject Debug -> Start new instance. Before, I needed to again manually attach the project to the process.

My Debug properties were, C:\Program Files (x86)\NUnit 2.6.4\bin\nunit.exe with argument of the location of the .dll to be tested.

More information: nunit for testing with .NET 4.0

Answer 19

See if this helps.. How to add NUnit in Visual Studio

(RighteousRant)Although personally I don't like this approach.. If you need a debugger while you are test-driving your code, it's a "smell" in that you do not have enough confidence/know how your code works & need the debugger to tell you that. TDD should free you from needing a debugger if done right. Use 'Attach debugger to NUNit' only for rare cases or when you are wading in someone else's code.