找不到WebApi控制器测试方法

Question

I have a very simple WebAPI 2 controller running on .NET Framework 4.6.2, that looks like this:

[RoutePrefix("Invitations")]
public class InvitationsController : CqrsApiController
{
    [HttpPost, Route("Clients/{id:long}/Actions/Cancel")]
    public IHttpActionResult PostClientInvitationCancel(long id, [FromBody] ClientInvitationCancelCommand command)
    {
        Execute(command);
        return SeeOther("Invitations/Clients/{0}", id);
    }
}

and am trying to write an NUnit test for it, like this:

[TestFixture]
public class WhenExecutingAValidCommand
{
    [Test]
    public void ItShouldReturnARedirect()
    {
        var dispatcher = Substitute.For<ICqrsDispatcher>();
        var urlHelper = Substitute.For<UrlHelper>();
        urlHelper.Link(Arg.Any<string>(), Arg.Any<object>()).Returns("https://tempuri.org/");

        var sut = new InvitationsController(dispatcher);
        sut.Request = new HttpRequestMessage();
        sut.Configuration = new HttpConfiguration();
        sut.Url = urlHelper;

        var response = sut.PostClientInvitationCancel(1, new ClientInvitationCancelCommand());
        response.Should().BeOfType<SeeOtherRedirectResult>();
    }
}

```

However, when I run the test, I get the following error:

System.MissingMethodException : Method not found: 'Void System.Web.Http.ApiController.set_Request(System.Net.Http.HttpRequestMessage)'.
   at ApiProjectTests.InvitationsControllerTests.WhenExecutingAValidCommand.ItShouldReturnARedirect()

The same code seems to work fine in similar projects based on .NET Framework 4.5.1, so I'm wondering if there's some sort of DLL hell going on here. System.Web.Http is using Microsoft.AspNet.WebApi.Core.5.2.3 , whereas System.Net.Http is coming from the GAC (well, C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Professional\\MSBuild\\Microsoft\\Microsoft.NET.Build.Extensions\\net461\\lib\\System.Net.Http.dll to be more precise).

Update : if I try to debug into the unit test, the error occurs before I even enter the method. So although VS2017 compiles the tests just fine, when the test runner fires up, then everything falls apart. Sounds more like DLL hell to me.

Update 2 : if I comment out the setting of the request, then I can debug into the test method. If I then put in a breakpoint, and then use the Immediate window to directly set the request property, it works, and there is no Method not found error. I also disabled Resharper and used VS2017's Test Explorer to run the tests, in case R# was caching something, but it made no difference.

Answer 1

It looks like my problem is indeed DLL hell, more specifically the DLL hell referenced by https://github.com/dotnet/corefx/issues/25773 . The issue is caused by other NuGet packages that contain references to the newer version of System.Net.Http (4.2.0.0). The current solution appears to be to add a binding redirect to downgrade the assembly version to the expected version (4.0.0.0), but so far that has not helped me.

The solution that did work for me was to install the latest NuGet package of System.Net.Http, and use assembly binding redirects in my test project to ensure that it used the 4.2.0.0 version instead of 4.0.0.0.

Answer 2

This is often caused by early versions of nuget packages targeting .NET standard, which have dependencies on OOB ("out-of-band") packages. OOB packages are a kind of polyfill for dlls that are part of .NET framework but not .NET standard. Here is a very good explanation of what happened. In my case, the following helped:

• I identified the nuget package that had a dependency on the system.net.http 4.2.0 nuget package, and upgrade that package.

• The dependency was no longer present in the upgraded package, so i could uninstall the system.net.http 4.2.0 nuget package.

• The upgraded package of course still expects the reference to the system.net.http 4.0.0 assembly, so in case of doubt, you may reinstall the upgraded package to make sure that the assembly reference is in your *.csproj file.