From fb6da9a76788a3d79a10f3aee08f19866d27d84c Mon Sep 17 00:00:00 2001
From: zoereco <158379334+zoereco@users.noreply.github.com>
Date: Mon, 5 Feb 2024 10:49:05 +0100
Subject: [PATCH] test: add overflow test for coin Add (#19344)

---
 types/coin_test.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/types/coin_test.go b/types/coin_test.go
index 36cc32c8cf..734af669e1 100644
--- a/types/coin_test.go
+++ b/types/coin_test.go
@@ -2,6 +2,7 @@ package types_test
 
 import (
 	"fmt"
+	"math/big"
 	"strings"
 	"testing"
 
@@ -156,6 +157,9 @@ func (s *coinTestSuite) TestCoinsDenoms() {
 }
 
 func (s *coinTestSuite) TestAddCoin() {
+	// 2**256 - 1 value to check for overflows
+	maxUint256 := math.NewIntFromBigInt(new(big.Int).Sub(new(big.Int).Lsh(big.NewInt(1), 256), big.NewInt(1)))
+
 	cases := []struct {
 		inputOne    sdk.Coin
 		inputTwo    sdk.Coin
@@ -165,6 +169,10 @@ func (s *coinTestSuite) TestAddCoin() {
 		{sdk.NewInt64Coin(testDenom1, 1), sdk.NewInt64Coin(testDenom1, 1), sdk.NewInt64Coin(testDenom1, 2), false},
 		{sdk.NewInt64Coin(testDenom1, 1), sdk.NewInt64Coin(testDenom1, 0), sdk.NewInt64Coin(testDenom1, 1), false},
 		{sdk.NewInt64Coin(testDenom1, 1), sdk.NewInt64Coin(testDenom2, 1), sdk.NewInt64Coin(testDenom1, 1), true},
+
+		// addition cannot lead to a number with more than 256 bits
+		{sdk.NewCoin(testDenom1, maxUint256), sdk.NewCoin(testDenom1, math.NewInt(0)), sdk.NewCoin(testDenom1, maxUint256), false},
+		{sdk.NewCoin(testDenom1, maxUint256), sdk.NewCoin(testDenom1, math.NewInt(1)), sdk.NewInt64Coin(testDenom1, 1), true},
 	}
 
 	for tcIndex, tc := range cases {