Replace AuthenticationHandler for integration tests

Question

I have a webapp that uses Forms authentication for browser clients and also basic auth for api access to an odata source.

This works in production but now I am struggeling to make this testable.

I use the WebApplicationFactory approach and also managed to implement the test authentication handler as described here

https://docs.microsoft.com/aspnet/core/test/integration-tests?view=aspnetcore-3.1#mock-authentication

and my unit tests now work as expected.

However I had to add the Test-Scheme to my Authorize attribute.

    [Authorize(Roles = "admin", AuthenticationSchemes = "BasicAuthentication,Test")]
    [ODataRoutePrefix("Customers")]
    public class CustomerController : ODataController
    {

        public CustomerController()
        {
        }

        [ODataRoute, EnableQuery]
        public IActionResult Get()
        {

            var result = new List<Customers>();

            return Ok(result);

        }
    }

The result is that my tests work but in production I get an exception because the Test scheme is missing.

Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

System.InvalidOperationException: No authentication handler is registered for the scheme 'Test'. The registered schemes are: Identity.Application, Identity.External, Identity.TwoFactorRememberMe, Identity.TwoFactorUserId, BasicAuthentication. Did you forget to call AddAuthentication().Add[SomeAuthHandler]("Test",...)?
   at Microsoft.AspNetCore.Authentication.AuthenticationService.AuthenticateAsync(HttpContext context, String scheme)
   at Microsoft.AspNetCore.Authorization.Policy.PolicyEvaluator.AuthenticateAsync(AuthorizationPolicy policy, HttpContext context)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Now I would like to replace my real BasicAuthenticationHandler with the TestAuthHandler

                var basicAuth = services.SingleOrDefault(
                    s => s.ServiceType ==
                        typeof(BasicAuthenticationHandler));

                services.Remove(basicAuth);

                services
                    .AddAuthentication("BasicAuthentication")
                    .AddScheme<AuthenticationSchemeOptions, TestAuthHandler>("BasicAuthentication", options =>
                    {

                    });

But this fails because the scheme BasicAuthentication already exists.

How do I remove a already registered authenticaton scheme from an existing asp.net core webapp? AuthenticationOptions does not have a RemoveScheme method.

System.InvalidOperationException : Scheme already exists: BasicAuthentication
    Stack Trace:
       at Microsoft.AspNetCore.Authentication.AuthenticationOptions.AddScheme(String name, Action`1 configureBuilder)
   at Microsoft.AspNetCore.Authentication.AuthenticationBuilder.<>c__DisplayClass4_0`2.<AddSchemeHelper>b__0(AuthenticationOptions o)
   at Microsoft.Extensions.Options.ConfigureNamedOptions`1.Configure(String name, TOptions options)
   at Microsoft.Extensions.Options.OptionsFactory`1.Create(String name)
   at Microsoft.Extensions.Options.OptionsManager`1.<>c__DisplayClass5_0.<Get>b__0()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Microsoft.Extensions.Options.OptionsCache`1.GetOrAdd(String name, Func`1 createOptions)
   at Microsoft.Extensions.Options.OptionsManager`1.Get(String name)
   at Microsoft.Extensions.Options.OptionsManager`1.get_Value()
   at Microsoft.AspNetCore.Authentication.AuthenticationSchemeProvider..ctor(IOptions`1 options, IDictionary`2 schemes)
   at Microsoft.AspNetCore.Authentication.AuthenticationSchemeProvider..ctor(IOptions`1 options)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite singletonCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.Internal.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
   at Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass4_0.<UseMiddleware>b__0(RequestDelegate next)
   at Microsoft.AspNetCore.Builder.ApplicationBuilder.Build()
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Start(IHost host)
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateHost(IHostBuilder builder)
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.EnsureServer()
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateDefaultClient(DelegatingHandler[] handlers)
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateDefaultClient(Uri baseAddress, DelegatingHandler[] handlers)
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateClient(WebApplicationFactoryClientOptions options)
   at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateClient()

Answer 1

I was doing something similar, and I ended up replacing the IAuthenticationSchemeProvider service which is used by the Authentication middleware.

Mock Provider

    public class MockSchemeProvider : AuthenticationSchemeProvider
    {
        public MockSchemeProvider(IOptions<AuthenticationOptions> options)
            : base(options)
        {
        }

        protected MockSchemeProvider(
            IOptions<AuthenticationOptions> options,
            IDictionary<string, AuthenticationScheme> schemes
        )
            : base(options, schemes)
        {
        }

        public override Task<AuthenticationScheme> GetSchemeAsync(string name)
        {
            if (name == "Test")
            {
                var scheme = new AuthenticationScheme(
                    "Test",
                    "Test",
                    typeof(MockAuthenticationHandler)
                );
                return Task.FromResult(scheme);
            }

            return base.GetSchemeAsync(name);
        }
    }

Mock Handler

    public class MockAuthenticationHandler: AuthenticationHandler<AuthenticationSchemeOptions>
    {
        public MockAuthenticationHandler(
            IOptionsMonitor<AuthenticationSchemeOptions> options,
            ILoggerFactory logger,
            UrlEncoder encoder,
            ISystemClock clock
        )
            : base(options, logger, encoder, clock)
        {
        }

        protected override Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            var claims = new[] {...};
            var identity = new ClaimsIdentity(claims, "Test");
            var principal = new ClaimsPrincipal(identity);
            var ticket = new AuthenticationTicket(principal, "Test");

            return Task.FromResult(AuthenticateResult.Success(ticket));
        }
    }

Now just register the service with, because it's the last one added it will override the current one.

services.AddTransient<IAuthenticationSchemeProvider, MockSchemeProvider>();