无法找到 testhost.dll。请发布您的测试项目并重试

我有一个简单的 dotnet 核心类库，带有单个 XUnit 测试方法：

TestLib.csproj:
<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Test.SDK" Version="15.9.0" />
    <PackageReference Include="xunit" Version="2.4.1" />
    <PackageReference Include="xunit.runner.console" Version="2.4.1">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
      <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
      <PrivateAssets>all</PrivateAssets>
    </PackageReference>
    <PackageReference Include="xunit.runners" Version="2.0.0" />
  </ItemGroup>

</Project>

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);
        }
    }
}

如果我在 CLI 上输入项目并输入dotnet build项目构建。如果我输入dotnet test我明白了：

C:\git\Testing\TestLib> 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.

我需要更改什么才能运行测试？

如果有帮助的话，VS Code 也不会在其测试资源管理器中显示测试。

安装中Microsoft.NET.Test.Sdknuget 包管理器中的包解决了我的问题。