feat: add revisioned resync reducer

server/domain/sync_test.go

@@ -0,0 +1,51 @@
+package domain
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestRevisionedReplicaRejectsGapAndConvergesAfterAuthoritativeSnapshot(t *testing.T) {
+	r, err := NewReplicaResource(ResourceQueueTicket, "ticket-1", Queued)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := r.ApplyEvent(SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 2, State: Accepted}); !errors.Is(err, ErrRevisionGap) || !r.NeedsResync {
+		t.Fatalf("gap = %+v err=%v", r, err)
+	}
+	if err := r.ApplyEvent(SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 1, State: Proposed}); !errors.Is(err, ErrRevisionGap) {
+		t.Fatalf("event applied while resync required: %v", err)
+	}
+	if err := r.ReplaceSnapshot(2, Accepted); err != nil || r.NeedsResync {
+		t.Fatalf("snapshot = %+v err=%v", r, err)
+	}
+	if err := r.ApplyEvent(SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 3, State: Allocating}); err != nil || r.Revision != 3 {
+		t.Fatalf("resume = %+v err=%v", r, err)
+	}
+}
+
+func TestReplicaRejectsInvalidInitialState(t *testing.T) {
+	if _, err := NewReplicaResource(ResourceProposal, "proposal-1", Live); err == nil {
+		t.Fatal("invalid proposal state accepted")
+	}
+}
+
+func TestRevisionedReplicaMakesDuplicateAndOutOfOrderEventsIdempotent(t *testing.T) {
+	r, _ := NewReplicaResource(ResourceQueueTicket, "ticket-1", Queued)
+	event := SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 1, State: Proposed}
+	if err := r.ApplyEvent(event); err != nil {
+		t.Fatal(err)
+	}
+	if err := r.ApplyEvent(event); err != nil {
+		t.Fatal(err)
+	}
+	if err := r.ApplyEvent(SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 0, State: Queued}); err != nil {
+		t.Fatal(err)
+	}
+	if r.Revision != 1 || r.State != Proposed {
+		t.Fatalf("replay changed state: %+v", r)
+	}
+	if err := r.ApplyEvent(SyncEvent{Kind: ResourceQueueTicket, ResourceID: "ticket-1", Revision: 1, State: Accepted}); !errors.Is(err, ErrSyncConflict) {
+		t.Fatalf("same-revision conflict = %v", err)
+	}
+}