Merge pull request #583 from nspcc-dev/fix/gettx

consensus: return nil interface from getTx

pkg/consensus/consensus.go

@@ -253,7 +253,13 @@ func (s *service) getTx(h util.Uint256) block.Transaction {
 
 	tx, _, _ := s.Config.Chain.GetTransaction(h)
 
-	return tx
+	// this is needed because in case of absent tx dBFT expects to
+	// get nil interface, not a nil pointer to any concrete type
+	if tx != nil {
+		return tx
+	}
+
+	return nil
 }
 
 func (s *service) verifyBlock(b block.Block) bool {

pkg/consensus/consensus_test.go

@@ -56,6 +56,37 @@ func TestService_ValidatePayload(t *testing.T) {
 	})
 }
 
+func TestService_getTx(t *testing.T) {
+	srv := newTestService(t)
+
+	t.Run("transaction in mempool", func(t *testing.T) {
+		tx := newMinerTx(1234)
+		h := tx.Hash()
+
+		require.Equal(t, nil, srv.getTx(h))
+
+		item := core.NewPoolItem(tx, new(feer))
+		srv.Chain.GetMemPool().TryAdd(h, item)
+
+		got := srv.getTx(h)
+		require.NotNil(t, got)
+		require.Equal(t, h, got.Hash())
+	})
+
+	t.Run("transaction in local cache", func(t *testing.T) {
+		tx := newMinerTx(4321)
+		h := tx.Hash()
+
+		require.Equal(t, nil, srv.getTx(h))
+
+		srv.txx.Add(tx)
+
+		got := srv.getTx(h)
+		require.NotNil(t, got)
+		require.Equal(t, h, got.Hash())
+	})
+}
+
 func TestService_OnPayload(t *testing.T) {
 	srv := newTestService(t)