dotnet-test-nunit is the unit test runner for .NET Core for running unit tests with NUnit 3.

dotnet-test-nunit is still an alpha release, so you need to select show prereleases if you are using Visual Studio.

Your project.json in your test project should look like the following;

{
    "version": "1.0.0-*",

    "dependencies": {
        "NUnit": "3.5.0",
        "dotnet-test-nunit": "3.4.0-beta-3"
    },

    "testRunner": "nunit",

    "frameworks": {
        "netcoreapp1.0": {
            "imports": "portable-net45+win8",
            "dependencies": {
                "Microsoft.NETCore.App": {
                    "version": "1.0.0-*",
                    "type": "platform"
                }
            }
        }
    }
}

The lines of interest here are the dependency on dotnet-test-nunit. I have added "testRunner": "nunit" to specify NUnit 3 as the test adapter. I also had to add to the imports for both the test adapter and NUnit to resolve.

You can now run your tests using the Visual Studio Test Explorer, or by running dotnet test from the command line.

# Restore the NuGet packages
dotnet restore

# Run the unit tests in the current directory
dotnet test

# Run the unit tests in a different directory
dotnet test test/NUnitWithDotNetCoreRC2.Test

Note that the dotnet command line swallows blank lines and does not work with color. The NUnit test runner's output is in color, but you won't see it. These are known issues with the dotnet CLI and not an NUnit bug.