Tests using TestServer are not working when I UseMVC() in the test startup about testing

[srivathsah]

Please ignore this issue , closing it. Basically I was only referencing the .netcore web api project in my test project, not the actual .net core 2.0 nuget packages, therefore the Microsoft.AspNetCore.TestHost when referenced in the test project was including the minimum version required not the latest versions that were in the web api project. After included the Microsoft.AspNetCore.All's latest nugget, it is resolved

[seccijr]

For those receiving the error System.AggregateException : One or more errors occurred. (Method not found: 'Microsoft.Net.Http.Headers.MediaTypeHeaderValue Microsoft.Net.Http.Headers.MediaTypeHeaderValue.Parse(System.String)' when running Test project please add explicitly reference to Microsoft.AspNetCore.Mvc and Microsoft.AspNetCore.StaticFiles to your dependencies:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.0.0" />
....
  </ItemGroup>
</Project>

Do it in your csproj file of your Test project.