title: Visual Studio 2017 + .Net Core 2 Tests not executable
body: <p>I'm trying to set up some unit tests for a private project. Since I don't mind the exact runner, I tried NUnit, XUnit and MStest, but none worked so far.</p>
  
  <p>After some research, I cloned the official Microsoft repository here :<a href="https://github.com/dotnet/docs/blob/master/samples/core/getting-started/unit-testing-using-nunit/PrimeService.Tests/PrimeService_IsPrimeShould.cs" rel="noreferrer">https://github.com/dotnet/docs/blob/master/samples/core/getting-started/unit-testing-using-nunit/PrimeService.Tests/PrimeService_IsPrimeShould.cs</a> 
  But these tests can't be executed as well. When doing so, I get the following error in the output:</p>
  
  <blockquote>
    <p>System.ArgumentException: Illegal characters in path.    at
    System.IO.Path.CheckInvalidPathChars(String path, Boolean
    checkAdditional)    at System.IO.Path.Combine(String path1, String
    path2)    at
    Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Helpers.DotnetHostHelper.TryGetExecutablePath(String
    executableBaseName, String&amp; executablePath)    at
    Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Helpers.DotnetHostHelper.GetDotnetPath()
    at
    Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Hosting.DotnetTestHostManager.GetTestHostProcessStartInfo(IEnumerable<code>1
    sources, IDictionary</code>2 environmentVariables, TestRunnerConnectionInfo
    connectionInfo)    at
    Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyOperationManager.SetupChannel(IEnumerable`1
    sources, CancellationToken cancellationToken)    at
    Microsoft.VisualStudio.TestPlatform.CrossPlatEngine.Client.ProxyDiscoveryManager.DiscoverTests(DiscoveryCriteria
    discoveryCriteria, ITestDiscoveryEventsHandler2 eventHandler)</p>
  </blockquote>
  
  <p>I also checked out several SO answers like <a href="https://stackoverflow.com/questions/42861930/unit-tests-not-discovered-in-visual-studio-2017">Unit Tests not discovered in Visual Studio 2017</a> or <a href="https://stackoverflow.com/questions/43007761/how-to-run-nunit-tests-in-visual-studio-2017">How to run NUnit tests in Visual Studio 2017?</a>, but none of them fixed the problem.</p>
  
  <p>My Visual Studio 2017 Version is currently 15.6.0 and I'm also using ReSharper. It seems like this is a local environmental problem, unfortunately, I didn't find any hints regarding that problem. Has anyone a idea, how that problem could be solved?</p>