atomic-design-poc/backend/tests/BigRegister.Tests/ZgwDivergenceTests.cs

using System.Net;
using System.Net.Http.Json;
using BigRegister.Api.Contracts;
using BigRegister.Api.Data;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.Extensions.DependencyInjection;

namespace BigRegister.Tests;

/// <summary>
/// WP-60's required verification: a ZGW failure mid-submit must not leave the two write sides
/// silently diverged — it's flagged (<see cref="Aanvraag.ZgwError"/>, an audit row) instead.
/// Not an <see cref="IClassFixture{TFixture}"/> off <see cref="TestWebApplicationFactory"/>: that
/// fixture hardcodes <c>Zgw:Enabled=false</c>, so this builds its own factory the same way
/// <see cref="OpenZaakIntegrationTests"/> does, but with a stub primary handler
/// (<see cref="ZgwStubHandler"/>) instead of a live OpenZaak.
/// </summary>
public class ZgwDivergenceTests
{
  private const string ZrcBase = "https://oz.example/zaken/api/v1";
  private const string ZtBase = "https://oz.example/catalogi/api/v1";
  private const string ZaaktypeUrl = $"{ZtBase}/zaaktypen/zt-1";

  private static WebApplicationFactory<Program> Factory(ZgwStubHandler stub)
  {
    var dbPath = Path.Combine(Path.GetTempPath(), $"bigregister-zgw-divergence-{Guid.NewGuid():N}.db");
    return new WebApplicationFactory<Program>().WithWebHostBuilder(builder => builder
        .UseSetting("ConnectionStrings:AppDb", $"Data Source={dbPath}")
        .UseSetting("Zgw:Enabled", "true")
        .UseSetting("Zgw:ZrcBaseUrl", ZrcBase)
        .UseSetting("Zgw:ZtcBaseUrl", ZtBase)
        .UseSetting("Zgw:ClientId", "c")
        .UseSetting("Zgw:Secret", "s")
        .UseSetting("Zgw:Bronorganisatie", "123443210")
        .UseSetting("Zgw:VerantwoordelijkeOrganisatie", "123443210")
        .UseSetting("Zgw:ZaaktypeUrls:registratie", ZaaktypeUrl)
        .ConfigureServices(services => services.ConfigureHttpClientDefaults(b =>
            b.ConfigurePrimaryHttpMessageHandler(() => stub))));
  }

  /// <summary>Doesn't call GET /applications first (unlike ApplicationTests.Create) — under
  /// Zgw:Enabled=true that route goes through IZaakSource too, which this test's stub doesn't
  /// need to answer since every test here uses a fresh db and creates exactly one aanvraag.</summary>
  private static async Task<string> CreateConcept(HttpClient client, string type = "registratie")
  {
    var res = await client.PostAsJsonAsync("/api/v1/applications", new { type });
    res.EnsureSuccessStatusCode();
    var body = (await res.Content.ReadFromJsonAsync<ApplicationDetailDto>())!;
    return body.Id;
  }

  private static string SuccessBody(string url) => url switch
  {
    _ when url == $"{ZrcBase}/zaken" => $$"""
      { "url": "{{ZrcBase}}/zaken/uuid-new", "identificatie": "BIG-2026-000123",
        "zaaktype": "{{ZaaktypeUrl}}", "startdatum": "2026-07-30",
        "einddatum": null, "registratiedatum": "2026-07-30" }
      """,
    _ when url.StartsWith($"{ZtBase}/statustypen") => """
      { "count": 1, "next": null,
        "results": [ { "url": "https://oz.example/catalogi/api/v1/statustypen/st-1", "volgnummer": 1 } ] }
      """,
    _ when url.StartsWith($"{ZtBase}/roltypen") => """
      { "count": 1, "next": null,
        "results": [ { "url": "https://oz.example/catalogi/api/v1/roltypen/rt-initiator" } ] }
      """,
    _ when url == $"{ZrcBase}/statussen" => "{}",
    _ when url == $"{ZrcBase}/rollen" => "{}",
    _ => throw new InvalidOperationException($"unexpected ZGW call {url}"),
  };

  [Fact]
  public async Task Submit_with_a_failing_zgw_flags_the_divergence_instead_of_diverging_silently()
  {
    var stub = new ZgwStubHandler(SuccessBody, (url, _) => url == $"{ZrcBase}/zaken" ? HttpStatusCode.ServiceUnavailable : HttpStatusCode.OK);
    using var factory = Factory(stub);
    using var client = factory.CreateClient();

    var id = await CreateConcept(client);
    var res = await client.PostAsJsonAsync($"/api/v1/applications/{id}/submit", new { diplomaHerkomst = "duo" });

    // The local write is still authoritative: 200 with a real reference, not a 500.
    res.EnsureSuccessStatusCode();
    var body = (await res.Content.ReadFromJsonAsync<SubmitApplicationResponse>())!;
    Assert.NotEmpty(body.Referentie);

    var stored = ApplicationStore.ListAll().Single(a => a.Id == id);
    Assert.Null(stored.ZaakUrl);
    Assert.NotNull(stored.ZgwError);

    var audit = await client.SendAsync(AdminRequest(HttpMethod.Get, "/api/v1/admin/audit"));
    audit.EnsureSuccessStatusCode();
    var entries = (await audit.Content.ReadFromJsonAsync<List<AuthzAuditDto>>())!;
    Assert.Contains(entries, e => e.Action == "zgw:divergence" && e.Decision == "deny" && e.Resource == body.Referentie);
  }

  [Fact]
  public async Task Submit_with_a_healthy_zgw_leaves_no_divergence_flag()
  {
    var stub = new ZgwStubHandler(SuccessBody);
    using var factory = Factory(stub);
    using var client = factory.CreateClient();

    var id = await CreateConcept(client);
    var res = await client.PostAsJsonAsync($"/api/v1/applications/{id}/submit", new { diplomaHerkomst = "duo" });
    res.EnsureSuccessStatusCode();

    var stored = ApplicationStore.ListAll().Single(a => a.Id == id);
    Assert.Equal($"{ZrcBase}/zaken/uuid-new", stored.ZaakUrl);
    Assert.Null(stored.ZgwError);
  }

  private static HttpRequestMessage AdminRequest(HttpMethod method, string path)
  {
    var req = new HttpRequestMessage(method, path);
    req.Headers.Add("X-Role", "admin");
    return req;
  }
}