title: Unable to find testhost.dll. Please publish your test project and retry
body: <p>I have a simple dotnet core class library with a single XUnit test method:</p>
  
  <pre><code>TestLib.csproj:
  &lt;Project Sdk="Microsoft.NET.Sdk"&gt;
  
    &lt;PropertyGroup&gt;
      &lt;TargetFramework&gt;netstandard2.0&lt;/TargetFramework&gt;
    &lt;/PropertyGroup&gt;
  
    &lt;ItemGroup&gt;
      &lt;PackageReference Include="Microsoft.NET.Test.SDK" Version="15.9.0" /&gt;
      &lt;PackageReference Include="xunit" Version="2.4.1" /&gt;
      &lt;PackageReference Include="xunit.runner.console" Version="2.4.1"&gt;
        &lt;IncludeAssets&gt;runtime; build; native; contentfiles; analyzers&lt;/IncludeAssets&gt;
        &lt;PrivateAssets&gt;all&lt;/PrivateAssets&gt;
      &lt;/PackageReference&gt;
      &lt;PackageReference Include="xunit.runner.visualstudio" Version="2.4.1"&gt;
        &lt;IncludeAssets&gt;runtime; build; native; contentfiles; analyzers&lt;/IncludeAssets&gt;
        &lt;PrivateAssets&gt;all&lt;/PrivateAssets&gt;
      &lt;/PackageReference&gt;
      &lt;PackageReference Include="xunit.runners" Version="2.0.0" /&gt;
    &lt;/ItemGroup&gt;
  
  &lt;/Project&gt;
  
  BasicTest.cs:
  using Xunit;
  
  namespace TestLib
  {
      public class BasicTest
      {
          [Fact(DisplayName = "Basic unit test")]
          [Trait("Category", "unit")]
          public void TestStringHelper()
          {
              var sut = "sut";
              var verify = "sut";
  
              Assert.Equal(sut, verify);
          }
      }
  }
  </code></pre>
  
  <p>If I enter the project on the CLI and type <code>dotnet build</code> the project builds. If I type <code>dotnet test</code> I get this:</p>
  
  <pre><code>C:\git\Testing\TestLib&gt; dotnet test
  C:\git\Testing\TestLib\TestLib.csproj : warning NU1701: Package 'xunit.runner.visualstudio 2.4.1' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
  Build started, please wait...
  C:\git\Testing\TestLib\TestLib.csproj : warning NU1701: Package 'xunit.runner.visualstudio 2.4.1' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
  Build completed.
  
  Test run for C:\git\Testing\TestLib\bin\Debug\netstandard2.0\TestLib.dll(.NETStandard,Version=v2.0)
  Microsoft (R) Test Execution Command Line Tool Version 16.0.0-preview-20181205-02
  Copyright (c) Microsoft Corporation.  All rights reserved.
  
  Starting test execution, please wait...
  Unable to find C:\git\Testing\TestLib\bin\Debug\netstandard2.0\testhost.dll. Please publish your test project and retry.
  
  Test Run Aborted.
  </code></pre>
  
  <p>What do I need to change to get the test to run?</p>
  
  <p>If it helps, VS Code is not displaying the tests in its test explorer, either.</p>