test(bff): endpoints, JWT auth and public-safe projection (refs #8)

Failing tests for the BFF walking-skeleton endpoints:
- POST /self-service/registrations rejects missing/malformed/wrong-key/expired
  tokens (401) and, with a valid digid token, forwards the bsn to the domain and
  returns 202 (WebApplicationFactory + a local test signing key, ADR-0010).
- GET /openbaar/register serves public-safe rows anonymously (never the bsn) and
  filters by q.
- OpenbaarProjection.PublicView (pure) filters by id and maps to id+status only.

Endpoints and PublicView are stubs so the tests compile and fail on their
assertions; the green commit implements them.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

services/bff/Bff.Tests/BffFactory.cs

@@ -0,0 +1,78 @@
+using System.Text;
+using Bff.Api;
+using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.IdentityModel.Protocols.OpenIdConnect;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Bff.Tests;
+
+/// <summary>
+/// Test host for the BFF. It swaps the downstream clients for in-memory fakes and reconfigures the
+/// JWT bearer to validate against a local test key (no live Keycloak) — so token validation is
+/// exercised in-process with tokens the tests mint (ADR-0010).
+/// </summary>
+internal sealed class BffFactory : WebApplicationFactory<Program>
+{
+    public static readonly SymmetricSecurityKey TestSigningKey =
+        new(Encoding.UTF8.GetBytes("bff-test-signing-key-that-is-at-least-256-bits-long!"));
+
+    public FakeDomainClient Domain { get; } = new();
+    public FakeProjectionClient Projection { get; } = new();
+
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        builder.UseSetting("Keycloak:Authority", "https://keycloak.invalid/realms/digid");
+        builder.UseSetting("Downstream:Domain:BaseUrl", "http://domain.invalid/");
+        builder.UseSetting("Downstream:Projection:BaseUrl", "http://projection.invalid/");
+
+        builder.ConfigureTestServices(services =>
+        {
+            services.AddSingleton<IDomainClient>(Domain);
+            services.AddSingleton<IProjectionClient>(Projection);
+
+            services.Configure<JwtBearerOptions>(JwtBearerDefaults.AuthenticationScheme, options =>
+            {
+                // Validate locally against the test key; never reach out for OIDC metadata.
+                options.Authority = null;
+                options.MetadataAddress = null!;
+                options.RequireHttpsMetadata = false;
+                options.Configuration = new OpenIdConnectConfiguration();
+                options.TokenValidationParameters = new TokenValidationParameters
+                {
+                    ValidateIssuer = false,
+                    ValidateAudience = false,
+                    ValidateLifetime = true,
+                    ValidateIssuerSigningKey = true,
+                    IssuerSigningKey = TestSigningKey,
+                    ClockSkew = TimeSpan.Zero,
+                };
+            });
+        });
+    }
+}
+
+/// <summary>Captures the bsn the BFF forwarded and returns a canned acceptance.</summary>
+internal sealed class FakeDomainClient : IDomainClient
+{
+    public string? SubmittedBsn { get; private set; }
+    public SubmitAccepted Result { get; set; } = new("reg-123", "Ingediend");
+
+    public Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default)
+    {
+        SubmittedBsn = bsn;
+        return Task.FromResult(Result);
+    }
+}
+
+/// <summary>Serves a configurable set of projection rows.</summary>
+internal sealed class FakeProjectionClient : IProjectionClient
+{
+    public List<ProjectionEntry> Entries { get; } = [];
+
+    public Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default)
+        => Task.FromResult<IReadOnlyList<ProjectionEntry>>(Entries);
+}

services/bff/Bff.Tests/OpenbaarEndpointTests.cs

@@ -0,0 +1,38 @@
+using System.Net;
+using System.Net.Http.Json;
+using Bff.Api;
+
+namespace Bff.Tests;
+
+public class OpenbaarEndpointTests
+{
+    [Fact]
+    public async Task Serves_public_safe_rows_anonymously()
+    {
+        using var factory = new BffFactory();
+        factory.Projection.Entries.Add(new ProjectionEntry("abc-111", "INGEDIEND", "123456782", "Jan"));
+
+        // No Authorization header — the openbaar register is a public lookup (ADR-0010/S-09).
+        var response = await factory.CreateClient().GetAsync("/openbaar/register");
+
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var body = await response.Content.ReadAsStringAsync();
+        Assert.Contains("abc-111", body);
+        Assert.Contains("INGEDIEND", body);
+        // The bsn must never appear in a public response.
+        Assert.DoesNotContain("123456782", body);
+    }
+
+    [Fact]
+    public async Task Filters_by_the_query_parameter()
+    {
+        using var factory = new BffFactory();
+        factory.Projection.Entries.Add(new ProjectionEntry("abc-111", "INGEDIEND", null, null));
+        factory.Projection.Entries.Add(new ProjectionEntry("def-222", "INGEDIEND", null, null));
+
+        var rows = await factory.CreateClient()
+            .GetFromJsonAsync<List<OpenbaarEntry>>("/openbaar/register?q=abc");
+
+        Assert.Equal("abc-111", Assert.Single(rows!).Id);
+    }
+}

services/bff/Bff.Tests/OpenbaarProjectionTests.cs

@@ -0,0 +1,48 @@
+using Bff.Api;
+
+namespace Bff.Tests;
+
+public class OpenbaarProjectionTests
+{
+    private static readonly ProjectionEntry[] Sample =
+    [
+        new("abc-111", "INGEDIEND", "123456782", "Jan"),
+        new("def-222", "INGEDIEND", "987654321", "Piet"),
+    ];
+
+    [Fact]
+    public void Maps_every_row_to_public_safe_fields_when_no_query()
+    {
+        var view = OpenbaarProjection.PublicView(Sample, null);
+
+        Assert.Equal(2, view.Count);
+        Assert.Equal("abc-111", view[0].Id);
+        Assert.Equal("INGEDIEND", view[0].Status);
+    }
+
+    [Fact]
+    public void Public_view_exposes_only_id_and_status()
+    {
+        // OpenbaarEntry structurally carries only Id + Status — bsn/naam can never leak.
+        var props = typeof(OpenbaarEntry).GetProperties().Select(p => p.Name).ToArray();
+        Assert.Equal(["Id", "Status"], props);
+    }
+
+    [Theory]
+    [InlineData("abc", 1)]
+    [InlineData("ABC", 1)]
+    [InlineData("2", 1)]
+    [InlineData("zzz", 0)]
+    public void Filters_by_id_containing_the_query_case_insensitively(string q, int expected)
+    {
+        var view = OpenbaarProjection.PublicView(Sample, q);
+
+        Assert.Equal(expected, view.Count);
+    }
+
+    [Fact]
+    public void Blank_query_is_treated_as_no_filter()
+    {
+        Assert.Equal(2, OpenbaarProjection.PublicView(Sample, "   ").Count);
+    }
+}

services/bff/Bff.Tests/SelfServiceEndpointTests.cs

@@ -0,0 +1,75 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+
+namespace Bff.Tests;
+
+public class SelfServiceEndpointTests
+{
+    private static HttpRequestMessage Submit(string? bearer)
+    {
+        var request = new HttpRequestMessage(HttpMethod.Post, "/self-service/registrations")
+        {
+            Content = JsonContent.Create(new { }),
+        };
+        if (bearer is not null)
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", bearer);
+        return request;
+    }
+
+    [Fact]
+    public async Task Rejects_a_request_without_a_token()
+    {
+        using var factory = new BffFactory();
+        var client = factory.CreateClient();
+
+        var response = await client.SendAsync(Submit(bearer: null));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+        Assert.Null(factory.Domain.SubmittedBsn);
+    }
+
+    [Theory]
+    [InlineData("not-a-jwt")]
+    public async Task Rejects_a_malformed_token(string bearer)
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(bearer));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Rejects_a_token_signed_with_the_wrong_key()
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(TestTokens.WrongKey("123456782")));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Rejects_an_expired_token()
+    {
+        using var factory = new BffFactory();
+        var response = await factory.CreateClient().SendAsync(Submit(TestTokens.Expired("123456782")));
+
+        Assert.Equal(HttpStatusCode.Unauthorized, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Accepts_a_valid_token_and_forwards_the_bsn_to_the_domain()
+    {
+        using var factory = new BffFactory();
+        var client = factory.CreateClient();
+
+        var response = await client.SendAsync(Submit(TestTokens.Valid("123456782")));
+
+        Assert.Equal(HttpStatusCode.Accepted, response.StatusCode);
+        Assert.Equal("123456782", factory.Domain.SubmittedBsn);
+        var body = await response.Content.ReadFromJsonAsync<SubmitAcceptedDto>();
+        Assert.Equal("reg-123", body!.RegistrationId);
+    }
+
+    private sealed record SubmitAcceptedDto(string RegistrationId, string Status);
+}

services/bff/Bff.Tests/TestTokens.cs

@@ -0,0 +1,30 @@
+using System.Text;
+using Microsoft.IdentityModel.JsonWebTokens;
+using Microsoft.IdentityModel.Tokens;
+
+namespace Bff.Tests;
+
+/// <summary>Mints JWTs for the BFF tests — signed with the factory's test key (valid) or otherwise
+/// (a wrong key / expired) to exercise the bearer validation the BFF configures.</summary>
+internal static class TestTokens
+{
+    public static string Valid(string bsn) => Create(bsn, BffFactory.TestSigningKey, expired: false);
+
+    public static string Expired(string bsn) => Create(bsn, BffFactory.TestSigningKey, expired: true);
+
+    public static string WrongKey(string bsn) => Create(
+        bsn,
+        new SymmetricSecurityKey(Encoding.UTF8.GetBytes("a-different-signing-key-256-bits-long-indeed-yes!")),
+        expired: false);
+
+    private static string Create(string bsn, SymmetricSecurityKey key, bool expired)
+    {
+        var handler = new JsonWebTokenHandler();
+        return handler.CreateToken(new SecurityTokenDescriptor
+        {
+            Claims = new Dictionary<string, object> { ["bsn"] = bsn },
+            Expires = DateTime.UtcNow.AddMinutes(expired ? -5 : 30),
+            SigningCredentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256),
+        });
+    }
+}