[ENG-681]: Comet ReCheckTx fix for the app-side mempool (#53)

Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>

x/builder/ante/ante.go

@@ -39,6 +39,18 @@ func NewBuilderDecorator(ak keeper.Keeper, txDecoder sdk.TxDecoder, txEncoder sd
 // AnteHandle validates that the auction bid is valid if one exists. If valid it will deduct the entrance fee from the
 // bidder's account.
 func (ad BuilderDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
+	// If comet is re-checking a transaction, we only need to check if the transaction is in the application-side mempool.
+	if ctx.IsReCheckTx() {
+		contains, err := ad.mempool.Contains(tx)
+		if err != nil {
+			return ctx, err
+		}
+
+		if !contains {
+			return ctx, fmt.Errorf("transaction not found in application mempool")
+		}
+	}
+
 	auctionMsg, err := mempool.GetMsgAuctionBidFromTx(tx)
 	if err != nil {
 		return ctx, err

x/builder/ante/ante_test.go

@@ -244,7 +244,7 @@ func (suite *AnteTestSuite) TestAnteHandler() {
 			suite.Require().NoError(err)
 
 			// Insert the top bid into the mempool
-			mempool := mempool.NewAuctionMempool(suite.encodingConfig.TxConfig.TxDecoder(), 0)
+			mempool := mempool.NewAuctionMempool(suite.encodingConfig.TxConfig.TxDecoder(), suite.encodingConfig.TxConfig.TxEncoder(), 0)
 			if insertTopBid {
 				topAuctionTx, err := testutils.CreateAuctionTxWithSigners(suite.encodingConfig.TxConfig, topBidder, topBid, 0, timeout, []testutils.Account{})
 				suite.Require().NoError(err)

x/builder/keeper/keeper_test.go

@@ -64,6 +64,6 @@ func (suite *KeeperTestSuite) SetupTest() {
 	err := suite.builderKeeper.SetParams(suite.ctx, types.DefaultParams())
 	suite.Require().NoError(err)
 
-	suite.mempool = mempool.NewAuctionMempool(suite.encCfg.TxConfig.TxDecoder(), 0)
+	suite.mempool = mempool.NewAuctionMempool(suite.encCfg.TxConfig.TxDecoder(), suite.encCfg.TxConfig.TxEncoder(), 0)
 	suite.msgServer = keeper.NewMsgServerImpl(suite.builderKeeper)
 }