Visual Studio 2017 & .net Core - Tests not displaying

[rubensurf]

I have an issue where tests that used to run with Nunit 3 and Visual Studio 2015 .net core used to run just fine.
The NuGet packages in project.json that were used are:
"testRunner": "nunit",

"dependencies": {
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.0.1"
},
"NUnit": "3.4.0",
"dotnet-test-nunit": "3.4.0-beta-3"
},

"frameworks": {
"netcoreapp1.0": {
"imports": "dnxcore50"
}
}

After creating clean Visual Studio 2017 projects for .net core, I cannot see the unit tests displayed in the Test Explorer window.
This is the error that shows in the Tests window:
An exception occurred while test discoverer 'NUnit3TestDiscoverer' was loading tests. Exception: Could not load file or assembly 'System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. The system cannot find the file specified.
The Nuget packages used are:
dotnet-test-nunit: 3.4.0-beta-3
NUnit 3.6.1
NUnit3TestAdapter 3.7.0

Thanks,

[rprouse]

Visual Studio 2017 and the new csproj format for .NET Core changed the test adapter API, so the dotnet-test-nunit adapter is now deprecated. We are working on an updated adapter that works with .NET Core, but it won't be ready for a few weeks. In the meantime, you can switch your tests to be a self-executing console app using the NUnitLite package.

See nunit/dotnet-test-nunit#108