Give the forge's merges a durable consumer of their own: no max-deliver, no reset, a growing delay while held (issue 973)

internal/broker/controller_buckets_test.go

@@ -320,3 +320,51 @@ func TestTheMergeWindowsKeysExpireAndAWatcherHearsIt(t *testing.T) {
 		}
 	}
 }
+
+// **The merges have a consumer of their own, which a reset of the events consumer leaves alone** (issue 973, novox/hq
+// ADR 0407 decision 3): healer H4 re-makes the events consumer from now, dropping what it holds pending; a merge
+// waiting in the merges consumer is not that consumer's, and nothing would catch it up.
+func TestAResetOfTheEventsConsumerLeavesTheMergesAndTheirConsumerAlone(t *testing.T) {
+	js, err := Dial(testbus.URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer js.Close()
+	if err := AssertMeshStreams(js); err != nil {
+		t.Fatal(err)
+	}
+	if err := AssertMeshConsumers(js); err != nil {
+		t.Fatal(err)
+	}
+	for _, c := range MeshConsumers() {
+		if c.Stream == EventsStream && c.Name == MergesConsumerName {
+			if c.Resettable != "" || c.MaxDeliver != 0 || len(c.Filters) != 1 || c.Filters[0] != ControllerFollows[3] {
+				t.Errorf("the merges consumer is %+v; want one filter, no max-deliver, not resettable", c)
+			}
+		}
+		if c.Stream == EventsStream && c.Name == ControllerName {
+			for _, f := range c.Filters {
+				if f == ControllerFollows[3] {
+					t.Errorf("the events consumer still follows the merges, which the merges consumer takes")
+				}
+			}
+		}
+	}
+	if _, err := js.Context().Publish(ControllerFollows[3], []byte(`{"commit":"c1"}`)); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := js.Context().Publish(ControllerFollows[0], []byte(`{}`)); err != nil {
+		t.Fatal(err)
+	}
+	merges, err := js.Context().ConsumerInfo(EventsStream, MergesConsumerName)
+	if err != nil || merges.NumPending != 1 {
+		t.Fatalf("the merges consumer holds %v (%v); want the merge", merges, err)
+	}
+	if _, _, err := js.ResetConsumer(EventsStream, ControllerName); err != nil {
+		t.Fatal(err)
+	}
+	merges, err = js.Context().ConsumerInfo(EventsStream, MergesConsumerName)
+	if err != nil || merges.NumPending != 1 || merges.Delivered.Stream != 0 {
+		t.Fatalf("after the reset the merges consumer holds %+v (%v); want its merge left alone", merges, err)
+	}
+}