aspnetcore: Integration testing is hard to set up and may break on shared framework servicing

Sort of a follow-up to @poke’s https://github.com/dotnet/sdk/issues/2253 but orthogonal.

TL;DR: Unit tests should have an option to run on the asp.net core shared framework using the same servicing strategy that the main subject-under-test application uses, which means referencing the shared framework using the latest known version of the web SDK and applying NuGet and assembly resolution accordingly.

Story: As a developer, I want to add a new test project with a reference to my asp.net core project so that I can write integration tests.

Naive steps:

• dotnet new razor -o …/RazorPagesProject
• dotnet new xunit
• dotnet add reference …/RazorPagesProject
• dotnet add package Microsoft.AspNetCore.Mvc.Testing -v 2.1.0-rc1-final
• add C# code

    public class SampleIntegrationTests : IClassFixture<WebApplicationFactory<Startup>>
    {
        public HttpClient Client { get; }

        public SampleIntegrationTests(WebApplicationFactory<Startup> fixture)
        {
            Client = fixture.CreateDefaultClient();
        }

        [Fact]
        public async Task ItShallWork()
        {
            var response = await Client.GetAsync("/");
            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
        }
    }

• dotnet test

Expected: Test passes

Actual:

Starting test execution, please wait...
[xUnit.net 00:00:00.5209160]   Discovering: SampleTests
[xUnit.net 00:00:00.5793000]   Discovered:  SampleTests
[xUnit.net 00:00:00.5854810]   Starting:    SampleTests
[xUnit.net 00:00:00.7291840]     SampleTests.SampleIntegrationTests.ItShallWork [FAIL]
[xUnit.net 00:00:00.7305700]       System.IO.FileNotFoundException : Could not load file or assembly 'Microsoft.AspNetCore, Version=2.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.
[xUnit.net 00:00:00.7306390]
[xUnit.net 00:00:00.7461290]   Finished:    SampleTests
Failed   SampleTests.SampleIntegrationTests.ItShallWork
Error Message:
 System.IO.FileNotFoundException : Could not load file or assembly 'Microsoft.AspNetCore, Version=2.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. Thesystem cannot find the file specified.

Workaround: Add a Package reference to the test project (!):

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.1.0-rc1-final" />
</ItemGroup>

What I really want:

• It should just work ™️
• Integration tests shall run on the asp.net core shared framework
• Integration tests shall use the same patch level of asp.net core components that dotnet run or dotnet publish + dotnet myapp.dll would use

What could be done here? a web-test-SDK maybe?