From 611265af76efb5f29755ba251059d104e7980c05 Mon Sep 17 00:00:00 2001
From: Emmanuel T Odeke <emmanuel@orijtech.com>
Date: Sat, 10 Dec 2022 06:59:05 -0800
Subject: [PATCH] test: types/query: add fuzzer for Paginate (#14239)

---
 types/query/fuzz_test.go | 97 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 types/query/fuzz_test.go

diff --git a/types/query/fuzz_test.go b/types/query/fuzz_test.go
new file mode 100644
index 0000000000..b0da0d39d6
--- /dev/null
+++ b/types/query/fuzz_test.go
@@ -0,0 +1,97 @@
+package query_test
+
+import (
+	"fmt"
+	"testing"
+
+	"cosmossdk.io/math"
+	"github.com/google/gofuzz"
+
+	"github.com/cosmos/cosmos-sdk/store/prefix"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/address"
+	"github.com/cosmos/cosmos-sdk/types/query"
+	"github.com/cosmos/cosmos-sdk/x/bank/testutil"
+	"github.com/cosmos/cosmos-sdk/x/bank/types"
+)
+
+type fuzzTestSuite struct {
+	paginationTestSuite
+}
+
+func FuzzPagination(f *testing.F) {
+	if testing.Short() {
+		f.Skip("In -short mode")
+	}
+
+	suite := new(fuzzTestSuite)
+	suite.SetT(new(testing.T))
+	suite.SetupTest()
+
+	gf := fuzz.New()
+	// 1. Set up some seeds.
+	seeds := []*query.PageRequest{
+		new(query.PageRequest),
+		&query.PageRequest{
+			Offset: 0,
+			Limit:  10,
+		},
+	}
+
+	// 1.5. Use the inprocess fuzzer to mutate variables.
+	for i := 0; i < 1000; i++ {
+		qr := new(query.PageRequest)
+		gf.Fuzz(qr)
+		seeds = append(seeds, qr)
+	}
+
+	// 2. Now serialize the fuzzers to bytes so that future mutations
+	// can occur.
+	for _, seed := range seeds {
+		seedBlob, err := suite.cdc.Marshal(seed)
+		if err == nil { // Some seeds could have been invalid so only add those that marshal.
+			f.Add(seedBlob)
+		}
+	}
+
+	// 3. Setup the keystore.
+	var balances sdk.Coins
+	for i := 0; i < 5; i++ {
+		denom := fmt.Sprintf("foo%ddenom", i)
+		balances = append(balances, sdk.NewInt64Coin(denom, int64(100+i)))
+	}
+
+	balances = balances.Sort()
+	addr1 := sdk.AccAddress([]byte("addr1"))
+	acc1 := suite.accountKeeper.NewAccountWithAddress(suite.ctx, addr1)
+	suite.accountKeeper.SetAccount(suite.ctx, acc1)
+	err := testutil.FundAccount(suite.bankKeeper, suite.ctx, addr1, balances)
+	if err != nil { // should return no error
+		f.Fatal(err)
+	}
+
+	// 4. Now run that fuzzer!
+	f.Fuzz(func(t *testing.T, pagBz []byte) {
+		qr := new(query.PageRequest)
+		if err := suite.cdc.Unmarshal(pagBz, qr); err != nil {
+			// Some pagination requests won't unmarshal and that's okay.
+			return
+		}
+
+		// Now try to paginate it.
+		req := types.NewQueryAllBalancesRequest(addr1, qr)
+		balResult := sdk.NewCoins()
+		authStore := suite.ctx.KVStore(suite.app.UnsafeFindStoreKey(types.StoreKey))
+		balancesStore := prefix.NewStore(authStore, types.BalancesPrefix)
+		accountStore := prefix.NewStore(balancesStore, address.MustLengthPrefix(addr1))
+		_, _ = query.Paginate(accountStore, req.Pagination, func(key []byte, value []byte) error {
+			var amount math.Int
+			err := amount.Unmarshal(value)
+			if err != nil {
+				return err
+			}
+			balResult = append(balResult, sdk.NewCoin(string(key), amount))
+			return nil
+		})
+	})
+}