Integration testing with in-memory IdentityServer

Question

I have an API that uses IdentityServer4 for token validation. I want to unit test this API with an in-memory TestServer. I\'d like to host the IdentityServer in the in-memor

Answer 1

We stepped away from trying to host a mock IdentityServer and used dummy/mock authorizers as suggested by others here.

Here's how we did that in case it's useful:

Created a function which takes a type, creates a test Authentication Middleware and adds it to the DI engine using ConfigureTestServices (so that it's called after the call to Startup.)

internal HttpClient GetImpersonatedClient() where T : AuthenticationHandler
    {
        var _apiFactory = new WebApplicationFactory();

        var client = _apiFactory
            .WithWebHostBuilder(builder =>
            {
                builder.ConfigureTestServices(services =>
                {
                    services.AddAuthentication("Test")
                        .AddScheme("Test", options => { });
                });
            })
            .CreateClient(new WebApplicationFactoryClientOptions
            {
                AllowAutoRedirect = false,
            });

        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Test");

        return client;
    }

Then we create what we called 'Impersonators' (AuthenticationHandlers) with the desired roles to mimic users with roles (We actually used this as a base class, and create derived classes based on this to mock different users):

public abstract class FreeUserImpersonator : AuthenticationHandler
{
    public Impersonator(
        IOptionsMonitor options,
        ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock)
        : base(options, logger, encoder, clock)
    {
        base.claims.Add(new Claim(ClaimTypes.Role, "FreeUser"));
    }

    protected List claims = new List();

    protected override Task HandleAuthenticateAsync()
    {
        var identity = new ClaimsIdentity(claims, "Test");
        var principal = new ClaimsPrincipal(identity);
        var ticket = new AuthenticationTicket(principal, "Test");

        var result = AuthenticateResult.Success(ticket);

        return Task.FromResult(result);
    }
}

Finally, we can perform our integration tests as follows:

// Arrange
HttpClient client = GetImpersonatedClient();

// Act
var response = await client.GetAsync("api/things");

// Assert
Assert.That.IsSuccessful(response);