WebApplicationFactory use ConfigureServices or ConfiguresTestServices

Question

I want to test a ASP.NET Core 6 application. I have created a custom factory as inheriting from WebApplicationFactory. In the ConfigureWebHost method, do I have to use builder.ConfigureServices or builder.ConfigureTestService ?

I don't understand the difference.

E.g :

        protected override void ConfigureWebHost(IWebHostBuilder builder)
        {
            builder
                .ConfigureTestServices(services => //Or ConfigureServices ?
                {
                    var descriptor = services.SingleOrDefault(
                        d => d.ServiceType ==
                            typeof(DbContextOptions<OnDemandContext>));

                    if (descriptor != null)
                    {
                        services.Remove(descriptor);
                    }
                    
                    services.AddDbContextPool<OnDemandContext>(options =>
                    {
                        options.UseInMemoryDatabase("fakeDatabase");
                    });
                });
        }

Answer 1

You don't have to call builder.ConfigureTestServices but it will allow you to re-configure, override, or replace previously registered services with something else. It is executed after your ConfigureServices method is called.

In the example below, testcontainers are used to replace the normal database connection string provider and a WebMotions.Fake.Authentication.JwtBearer is being used to create a fake Jwt bearer token for integration testing

    builder.ConfigureTestServices(services =>
    {
        services.AddAuthentication(FakeJwtBearerDefaults.AuthenticationScheme).AddFakeJwtBearer();
        services.RemoveAll(typeof(IHostedService));
        services.RemoveAll(typeof(IConnectionStringProvider));
        var containerString = new ConnectionStringOptions
        {
            Application = "testContainer",
            Primary = Container.ConnectionString
        };
        services.AddSingleton<IConnectionStringProvider>(_ =>
            new ConnectionStringProvider(containerString));
    });