services/event-subscriber/EventSubscriber.Tests/InMemoryStores.cs

@@ -20,8 +20,13 @@ internal sealed class InMemoryProjectionStore : IProjectionStore
 {
     private readonly Dictionary<string, RegisterEntry> _byId = [];
 
+    /// <summary>How many times a write was attempted — lets a test prove a deduped delivery
+    /// never reaches the store (an idempotent upsert hides the difference in row count alone).</summary>
+    public int UpsertCount { get; private set; }
+
     public Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default)
     {
+        UpsertCount++;
         _byId[entry.Id] = entry;
         return Task.CompletedTask;
     }

services/event-subscriber/EventSubscriber.Tests/NotificationProjectorTests.cs

@@ -38,32 +38,52 @@ public sealed class NotificationProjectorTests
     }
 
     [Fact]
-    public async Task a_notification_on_another_kanaal_is_ignored()
+    public async Task a_replayed_notification_never_reaches_the_projection_store()
-    {
-        await Projector().HandleAsync(new Notification("documenten", "enkelvoudiginformatieobject", "create", new Uri(ZaakUrl)));
-
-        Assert.Empty(await _store.AllAsync());
-    }
-
-    [Fact]
-    public async Task a_zaak_update_is_ignored_by_the_minimal_projection()
-    {
-        await Projector().HandleAsync(new Notification("zaken", "zaak", "update", new Uri(ZaakUrl)));
-
-        Assert.Empty(await _store.AllAsync());
-    }
-
-    [Fact]
-    public async Task rebuild_repopulates_the_projection_from_the_notification_log()
     {
         var projector = Projector();
         await projector.HandleAsync(ZaakCreated());
-        await _store.ClearAsync();
+        await projector.HandleAsync(ZaakCreated());
+
+        // The duplicate is dropped at the log, before the (idempotent) upsert — so the store
+        // is written exactly once. Row count alone can't see this; the upsert count can.
+        Assert.Equal(1, _store.UpsertCount);
+    }
+
+    [Fact]
+    public async Task two_different_zaken_each_get_their_own_row()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        await projector.HandleAsync(ZaakCreated(ZaakUrl[..^1] + "2")); // a distinct zaak url
+
+        Assert.Equal(2, (await _store.AllAsync()).Count);
+    }
+
+    [Theory]
+    [InlineData("documenten", "enkelvoudiginformatieobject", "create")] // wrong kanaal + resource
+    [InlineData("documenten", "zaak", "create")]                        // wrong kanaal only
+    [InlineData("zaken", "status", "create")]                           // wrong resource only
+    [InlineData("zaken", "zaak", "update")]                             // wrong actie
+    [InlineData("zaken", "zaak", "destroy")]                            // wrong actie
+    public async Task only_a_zaken_zaak_create_notification_is_projected(string kanaal, string resource, string actie)
+    {
+        await Projector().HandleAsync(new Notification(kanaal, resource, actie, new Uri(ZaakUrl)));
+
         Assert.Empty(await _store.AllAsync());
+    }
+
+    [Fact]
+    public async Task rebuild_clears_stale_rows_and_repopulates_from_the_notification_log()
+    {
+        var projector = Projector();
+        await projector.HandleAsync(ZaakCreated());
+        // A stale row that is not backed by any logged notification must not survive a rebuild.
+        await _store.UpsertAsync(new RegisterEntry("stale-9999", RegistrationStatus.Ingediend));
 
         await projector.RebuildAsync();
 
         var entry = Assert.Single(await _store.AllAsync());
+        Assert.Equal("11111111-1111-1111-1111-111111111111", entry.Id);
         Assert.Equal(RegistrationStatus.Ingediend, entry.Status);
     }
 }

services/event-subscriber/EventSubscriber.slnx

@@ -0,0 +1,4 @@
+<Solution>
+  <Project Path="EventSubscriber.Application/EventSubscriber.Application.csproj" />
+  <Project Path="EventSubscriber.Tests/EventSubscriber.Tests.csproj" />
+</Solution>

services/event-subscriber/stryker-config.json

@@ -0,0 +1,12 @@
+{
+  "stryker-config": {
+    "solution": "EventSubscriber.slnx",
+    "test-projects": ["EventSubscriber.Tests/EventSubscriber.Tests.csproj"],
+    "reporters": ["progress", "html"],
+    "thresholds": {
+      "high": 95,
+      "low": 90,
+      "break": 90
+    }
+  }
+}