Is there a free Visual Studio addin for Nunit?
Solution 1:
You can create a blank project (Choose console application for example) and in the property of the project you can select DEBUG tag and select "Start External Program". Put the path of Nunit. Then, in the start option, the command line arguments select the DLL that contains all your tests (mine is always in the nunit\bin...). Then select "enable unmanaged code debugging" and you will be able to start the project inside VS and even use the debugger step-by-step.
This is a free solution.
Solution 2:
Now you can use Gallio: it's open source. www.gallio.org
Solution 3:
By the way TestDriven can be downloaded for free if it's for personal use or Open Source project.
I had to find a way to use .Net Reflector inside VS few days ago and when I downloaded TestDriven it cames with. Never got any popup asking me to paid.
Solution 4:
NUnit actually ships with a basic integrated runner. It's not very good, and not very publicized, but unless Charlie has taken it out, it should be in the source.
Solution 5:
I know this is an old question but another way to do this is to add an external tool from the tools menu to run nunit - set the arguments to be $(TargetName)$(TargetExt) and initial directory to $(ProjectDir)\bin\Debug
check out this link