From 543929a7155222e0a7df098695cddb035e7085a8 Mon Sep 17 00:00:00 2001
From: William Banfield <wbanfield@gmail.com>
Date: Fri, 15 Oct 2021 14:07:56 -0400
Subject: [PATCH] add test for v0 mempool

---
 internal/mempool/v0/clist_mempool.go      |  2 +-
 internal/mempool/v0/clist_mempool_test.go | 52 +++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/internal/mempool/v0/clist_mempool.go b/internal/mempool/v0/clist_mempool.go
index 2cb69551f..0a12c7000 100644
--- a/internal/mempool/v0/clist_mempool.go
+++ b/internal/mempool/v0/clist_mempool.go
@@ -462,7 +462,7 @@ func (mem *CListMempool) resCbRecheck(req *abci.Request, res *abci.Response) {
 
 			mem.logger.Error(
 				"re-CheckTx transaction mismatch",
-				"got", tx,
+				"got", types.Tx(tx),
 				"expected", memTx.tx,
 			)
 
diff --git a/internal/mempool/v0/clist_mempool_test.go b/internal/mempool/v0/clist_mempool_test.go
index b61a8333e..0381d576a 100644
--- a/internal/mempool/v0/clist_mempool_test.go
+++ b/internal/mempool/v0/clist_mempool_test.go
@@ -13,9 +13,11 @@ import (
 	"github.com/gogo/protobuf/proto"
 	gogotypes "github.com/gogo/protobuf/types"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 
 	abciclient "github.com/tendermint/tendermint/abci/client"
+	abciclimocks "github.com/tendermint/tendermint/abci/client/mocks"
 	"github.com/tendermint/tendermint/abci/example/kvstore"
 	abciserver "github.com/tendermint/tendermint/abci/server"
 	abci "github.com/tendermint/tendermint/abci/types"
@@ -214,6 +216,56 @@ func TestMempoolUpdate(t *testing.T) {
 	}
 }
 
+func TestMempoolUpdateDoesNotPanicWhenApplicationMissedTx(t *testing.T) {
+	var callback abciclient.Callback
+	mockClient := new(abciclimocks.Client)
+	mockClient.On("Start").Return(nil)
+	mockClient.On("SetLogger", mock.Anything)
+
+	mockClient.On("Error").Return(nil).Times(4)
+	mockClient.On("FlushAsync", mock.Anything).Return(abciclient.NewReqRes(abci.ToRequestFlush()), nil)
+	mockClient.On("SetResponseCallback", mock.MatchedBy(func(cb abciclient.Callback) bool { callback = cb; return true }))
+
+	cc := func() (abciclient.Client, error) {
+		return mockClient, nil
+	}
+
+	mp, cleanup := newMempoolWithApp(cc)
+	defer cleanup()
+
+	// Add 4 transactions to the mempool by calling the mempool's `CheckTx` on each of them.
+	txs := []types.Tx{[]byte{0x01}, []byte{0x02}, []byte{0x03}, []byte{0x04}}
+	for _, tx := range txs {
+		reqRes := abciclient.NewReqRes(abci.ToRequestCheckTx(abci.RequestCheckTx{Tx: tx}))
+		reqRes.Response = abci.ToResponseCheckTx(abci.ResponseCheckTx{Code: abci.CodeTypeOK})
+		// SetDone allows the ReqRes to process its callback synchronously.
+		// This simulates the Response being ready for the client immediately.
+		reqRes.SetDone()
+
+		mockClient.On("CheckTxAsync", mock.Anything, mock.Anything).Return(reqRes, nil)
+		err := mp.CheckTx(context.Background(), tx, nil, mempool.TxInfo{})
+		require.NoError(t, err)
+	}
+
+	// Calling update to remove the first transaction from the mempool.
+	// This call also triggers the mempool to recheck its remaining transactions.
+	err := mp.Update(0, []types.Tx{txs[0]}, abciResponses(1, abci.CodeTypeOK), nil, nil)
+	require.Nil(t, err)
+
+	// The mempool has now sent its callbacks off to the client to be rechecked.
+	// We now call the mempool-supplied callback on the first and third transaction.
+	// This simulates the client dropping the second request.
+	// Previous versions of this code panicked when the ABCI application missed
+	// a recheck-tx request.
+	resp := abci.ResponseCheckTx{Code: abci.CodeTypeOK}
+	req := abci.RequestCheckTx{Tx: txs[1]}
+	callback(abci.ToRequestCheckTx(req), abci.ToResponseCheckTx(resp))
+
+	req = abci.RequestCheckTx{Tx: txs[3]}
+	callback(abci.ToRequestCheckTx(req), abci.ToResponseCheckTx(resp))
+	mockClient.AssertExpectations(t)
+}
+
 func TestMempool_KeepInvalidTxsInCache(t *testing.T) {
 	app := kvstore.NewApplication()
 	cc := abciclient.NewLocalCreator(app)