fix(11-08): refuse unmanaged after-commit work

modules/beachcomber/sync_test.go

@@ -337,8 +337,8 @@ func TestSyncGates(t *testing.T) {
 }
 
 // TestSyncAfterCommit covers D-20: a write syncs only after it commits
-// (lagoon.Transaction, a single statement's implicit transaction, a plain
-// gorm transaction through its handle), a rollback syncs nothing, and the
+// (lagoon.Transaction and a single statement's implicit transaction), a
+// foreign GORM transaction is refused, a rollback syncs nothing, and the
 // document is built from a reload on a clean statement.
 func TestSyncAfterCommit(t *testing.T) {
 	env := newSyncEnv(t, nil, true)
@@ -403,20 +403,22 @@ func TestSyncAfterCommit(t *testing.T) {
 		}
 	})
 
-	t.Run("plain_gorm_transaction_syncs_through_the_tx", func(t *testing.T) {
+	t.Run("plain_gorm_transaction_rollback_sends_nothing", func(t *testing.T) {
+		rollback := errors.New("roll back plain transaction")
 		err := env.gdb.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
 			if err := tx.Create(&Doc{Title: "plain-tx", OwnerID: 1}).Error; err != nil {
 				return err
 			}
-			calls := env.eng.take()
-			if len(calls) != 1 || calls[0].docs[0]["title"] != "plain-tx" {
-				t.Errorf("inside a plain transaction: calls = %+v, want an immediate sync from the uncommitted row", calls)
+			if calls := env.eng.take(); len(calls) != 0 {
+				t.Errorf("inside a plain transaction: calls = %+v, want none", calls)
 			}
-			// The transaction is still usable.
-			return tx.Create(&Plain{Name: "after"}).Error
+			return rollback
 		})
-		if err != nil {
-			t.Fatal(err)
+		if !errors.Is(err, rollback) {
+			t.Fatalf("err = %v", err)
+		}
+		if calls := env.eng.take(); len(calls) != 0 {
+			t.Fatalf("after rollback: calls = %+v, want none", calls)
 		}
 	})