add payload tx to mempool if not exists before engine api call

Author: gupadhyaya

execution.go

@@ -161,6 +161,15 @@ func (c *EngineClient) ExecuteTxs(ctx context.Context, txs [][]byte, blockHeight
 		if err != nil {
 			return nil, 0, fmt.Errorf("failed to unmarshal transaction: %w", err)
 		}
+		txHash := ethTxs[i].Hash()
+		_, isPending, err := c.ethClient.TransactionByHash(context.Background(), txHash)
+		if err == nil && isPending {
+			continue // skip SendTransaction
+		}
+		err = c.ethClient.SendTransaction(context.Background(), ethTxs[i])
+		if err != nil {
+			return nil, 0, fmt.Errorf("failed to send transaction: %w", err)
+		}
 	}
 
 	// encode

execution_test.go

@@ -105,7 +105,7 @@ func TestEngineExecution(t *testing.T) {
 
 			payload, err := executionClient.GetTxs(ctx)
 			require.NoError(tt, err)
-			require.Lenf(tt, payload, nTxs+1, "expected %d transactions, got %d", nTxs+1, len(payload))
+			require.Lenf(tt, payload, nTxs, "expected %d transactions, got %d", nTxs, len(payload))
 
 			allPayloads = append(allPayloads, payload)
 
@@ -180,7 +180,11 @@ func TestEngineExecution(t *testing.T) {
 			if len(payload) > 0 {
 				require.NotZero(tt, maxBytes)
 			}
-			require.NotEqual(tt, prevStateRoot, newStateRoot)
+			if len(payload) == 0 {
+				require.Equal(tt, prevStateRoot, newStateRoot)
+			} else {
+				require.NotEqual(tt, prevStateRoot, newStateRoot)
+			}
 
 			err = executionClient.SetFinal(ctx, blockHeight)
 			require.NoError(tt, err)