im writing integration tests but im currently stuck … one of scoped services require extra initialization step to set private field but when i try to call this extra step in test code it is not working as expected:

imagine this 3rd party service (this code i cannot change):

interface IScopedService {
    bool IsFooValid(int foo);
}
class ScopedService {
   private List<int> _Foo = new();
   public void Register(int foo){
      _Foo.Add(foo);
   }
   public bool IsFooValid(int foo){
      return _Foo.Contains(foo);
   }
}

that is used by my controller:

class MyController(IScopedService scopedServiceInController) : ApiController {
   [HttpPost]
   public bool MyFunc(int foo){
       return scopedServiceInController.IsFooValid(foo);
   }
}

which is called from client via:

class MyEndpoints(HttpClient httpClient) {
    public bool MyFunc(int foo){
        var request = new HttpRequestMessage(HttpMethod.Post, $"path") {
            Content = JsonContent.Create(foo)
        };

        var result = await httpClient.SendAsync(request);
        if (!result.IsSuccessStatusCode) {
            return null;
        }

        return await result.Content.ReadFromJson<bool>();
    }
}

and integration test for that:

class MyWebApplicationFactory: WebApplicationFactory<Program>, IAsyncLifetime {
    public  IServiceProvider ScopedServiceProvider => _Scope.ServiceProvider;
    private IServiceScope _Scope;

    public virtual async Task InitializeAsync() {
        _Scope = Services.CreateScope();
    }

    public new virtual async Task DisposeAsync() {
        _Scope.Dispose();
    }
}
class MyServiceTests: IClassFixture<MyWebApplicationFactory> {
    private readonly MyWebApplicationFactory _Factory;
    private readonly MyEndpoints _Sut;

    public MyServiceTests(MyWebApplicationFactory factory){
         _Factory = factory;

         var client = factory.CreateClient();
         _Sut = new MyEndpoints(client);
    }
    [Fact]
    public void Test(){
        // Arrange
        var scopedServiceInTest = _Factory.ScopedServiceProvider.GetRequiredService<ScopedService>();
        scopedServiceInTest.Register(1);

        // Act
        var actual = _Sut.MyFunc(1);

        // Assert
        actual.Should.BeTrue();      
    }
}
}

my troube is that scopedServiceInController is not same instance as scopedServiceInTest => foo list is not initialized => test will fail

my theory is that i should not create new scope in MyWebApplicationFactory but get instance of scope that server uses to resolve scopedServiceInController …

any idea how to fix this?

PS: in my code ScopedService is Microsoft.AspNetCore.Identity.UserManager<User> and i need to call RegisterTokenProvider method if that helps …