test(domain): werkbak query lists open beoordelingen enriched from the store (refs #13)

Red — the Werkbak use-case and WerkbakItem do not exist yet.

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

services/domain/Big.Tests/Fakes.cs

@@ -41,6 +41,29 @@ internal sealed class FakeWorkflowClient(string processInstanceId = "proc-1", Ac
     }
 }
 
+/// <summary>A fake user-task client for the werkbak/decision use cases: returns a scripted set of
+/// open beoordeling tasks and records claim/complete calls.</summary>
+internal sealed class FakeUserTaskClient(IReadOnlyList<BeoordelingTask> open) : IUserTaskClient
+{
+    public (string TaskId, string Behandelaar)? Claimed { get; private set; }
+    public (string TaskId, BeoordelingsBesluit Besluit)? Completed { get; private set; }
+
+    public Task<IReadOnlyList<BeoordelingTask>> GetOpenBeoordelingenAsync(CancellationToken ct = default)
+        => Task.FromResult(open);
+
+    public Task ClaimAsync(string taskId, string behandelaar, CancellationToken ct = default)
+    {
+        Claimed = (taskId, behandelaar);
+        return Task.CompletedTask;
+    }
+
+    public Task CompleteBeoordelingAsync(string taskId, BeoordelingsBesluit besluit, CancellationToken ct = default)
+    {
+        Completed = (taskId, besluit);
+        return Task.CompletedTask;
+    }
+}
+
 /// <summary>A fake ACL client that records the bsn it was asked to open a zaak for and returns a
 /// fixed zaak URL.</summary>
 internal sealed class FakeAclClient(Uri? zaakUrl = null) : IAclClient