You can download NCover using the links provided on the left. Once you have it downloaded, you install it (it comes as an msi file, even though I doubt it really needs anything but an xcopy deployment).
The documentation of NCover is, at the time of writing this, spotty at best. I fought with it a little bit before figuring out how to get it to work on a project. Because NCover is a command-line driven tool, after installing it, you'll probably want to add its path to your environment so that you can just call the NCover executable in the command-line--rather than typing in the full path to the executable each time. Assuming your installation put NCover in the same place as mine did (C:\Program Files\NCover), here is how to add it to your environmental path (on Windows XP Professional):
To use NCover, use a command line and navigate to where your nunit.console.exe file is. You then feed it the path to your project's NUnit suite of tests. Assuming the NUnit suite's dll is found at "C:\Development\Projects\NCoverExample\Test\bin\debug\Test.dll", and that you have one project to test (named "Domain"), you'd issue the following command-line directive:
ncover.console "nunit-console.exe" "C:\Development\Projects\NCoverExample\Test\bin\debug\Test.dll" /xml C:\Coverage\NunitOutput.xml //a Domain //l C:\Coverage\Coverage.log //x C:\Coverage\Coverage.xml
What we have above is issue a call to NCover, followed by a number of command-line arguments. Here is everything broken down in order:
ncover.console
(Call to NCover)
nunit-console.exe
(Tells NCover to run NUnit)
"C:\Development\Projects\NCoverExample\Test\bin\debug\Test.dll"
(Tells NUnit this is the test suite's dll)
/xml C:\Coverage\NUnitOutput.xml
(Tells NUnit to put its XML output here)
//a Domain
(Tells NCover this is the assembly we are interested in determining test coverage for. If you would like to determine the coverage for multiple assemblies then just list them all here, each separated by a semi-colon)
//l C:\Coverage\Coverage.log
(Tells NCover this is the coverage log file to write to)
//x C:\Coverage\Coverage.xml
(Tells NCover this is the coverage output file to write to. This is the file you will load into NCoverExplorer)
You'll notice in the above example I don't direct the NCover or NUnit output to a location near my source code because I don't want it to get accidentally committed to my source control repository.