fix zero coins

CHANGELOG.md

@@ -134,6 +134,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/bank) [\#8434](https://github.com/cosmos/cosmos-sdk/pull/8434) Fix legacy REST API `GET /bank/total` and `GET /bank/total/{denom}` in swagger
 * (x/slashing) [\#8427](https://github.com/cosmos/cosmos-sdk/pull/8427) Fix query signing infos command
 * (server) [\#8399](https://github.com/cosmos/cosmos-sdk/pull/8399) fix gRPC-web flag default value
+* (x/bank) [\#9229](https://github.com/cosmos/cosmos-sdk/pull/9229) Now zero coin balances cannot be added to balances & supply stores. If any denom becomes zero corresponding key gets deleted from store.
 
 ### Deprecated
 

x/bank/keeper/genesis_test.go

@@ -33,8 +33,6 @@ func (suite *IntegrationTestSuite) TestExportGenesis() {
 	suite.Require().Len(exportGenesis.Params.SendEnabled, 0)
 	suite.Require().Equal(types.DefaultParams().DefaultSendEnabled, exportGenesis.Params.DefaultSendEnabled)
 	suite.Require().Equal(totalSupply, exportGenesis.Supply)
-	// add mint module balance as nil
-	expectedBalances = append(expectedBalances, types.Balance{Address: "cosmos1m3h30wlvsf8llruxtpukdvsy0km2kum8g38c8q", Coins: nil})
 	suite.Require().Equal(expectedBalances, exportGenesis.Balances)
 	suite.Require().Equal(expectedMetadata, exportGenesis.DenomMetadata)
 }

x/bank/keeper/keeper.go

@@ -67,7 +67,9 @@ func (k BaseKeeper) GetPaginatedTotalSupply(ctx sdk.Context, pagination *query.P
 		if err != nil {
 			return fmt.Errorf("unable to convert amount string to Int %v", err)
 		}
-		supply = append(supply, sdk.NewCoin(string(key), amount))
+
+		// `Add` omits the 0 coins addition to the `supply`.
+		supply = supply.Add(sdk.NewCoin(string(key), amount))
 		return nil
 	})
 
@@ -426,14 +428,20 @@ func (k BaseKeeper) BurnCoins(ctx sdk.Context, moduleName string, amounts sdk.Co
 }
 
 func (k BaseKeeper) setSupply(ctx sdk.Context, coin sdk.Coin) {
-	store := ctx.KVStore(k.storeKey)
-	supplyStore := prefix.NewStore(store, types.SupplyKey)
-
 	intBytes, err := coin.Amount.Marshal()
 	if err != nil {
 		panic(fmt.Errorf("unable to marshal amount value %v", err))
 	}
-	supplyStore.Set([]byte(coin.GetDenom()), intBytes)
+
+	store := ctx.KVStore(k.storeKey)
+	supplyStore := prefix.NewStore(store, types.SupplyKey)
+
+	// incase of `coin` is zero remove it from `supplyStore` (this case can be possible when burning all coins).
+	if coin.IsZero() {
+		supplyStore.Delete([]byte(coin.Denom))
+	} else {
+		supplyStore.Set([]byte(coin.GetDenom()), intBytes)
+	}
 }
 
 func (k BaseKeeper) trackDelegation(ctx sdk.Context, addr sdk.AccAddress, balance, amt sdk.Coins) error {

x/bank/keeper/keeper_test.go

@@ -89,17 +89,51 @@ func (suite *IntegrationTestSuite) SetupTest() {
 }
 
 func (suite *IntegrationTestSuite) TestSupply() {
-	app, ctx := suite.app, suite.ctx
+	app := simapp.Setup(false)
+	ctx := app.BaseApp.NewContext(false, tmproto.Header{Height: 1})
+	appCodec := simapp.MakeTestEncodingConfig().Marshaler
+
+	// add module accounts to supply keeper
+	maccPerms := simapp.GetMaccPerms()
+	maccPerms[holder] = nil
+	maccPerms[authtypes.Burner] = []string{authtypes.Burner}
+	maccPerms[authtypes.Minter] = []string{authtypes.Minter}
+	maccPerms[multiPerm] = []string{authtypes.Burner, authtypes.Minter, authtypes.Staking}
+	maccPerms[randomPerm] = []string{"random"}
+
+	authKeeper := authkeeper.NewAccountKeeper(
+		appCodec, app.GetKey(types.StoreKey), app.GetSubspace(types.ModuleName),
+		authtypes.ProtoBaseAccount, maccPerms,
+	)
+	keeper := keeper.NewBaseKeeper(
+		appCodec, app.GetKey(types.StoreKey), authKeeper,
+		app.GetSubspace(types.ModuleName), make(map[string]bool),
+	)
 
 	initialPower := int64(100)
 	initTokens := suite.app.StakingKeeper.TokensFromConsensusPower(suite.ctx, initialPower)
-
 	totalSupply := sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, initTokens))
-	suite.NoError(app.BankKeeper.MintCoins(ctx, minttypes.ModuleName, totalSupply))
 
-	total, _, err := app.BankKeeper.GetPaginatedTotalSupply(ctx, &query.PageRequest{})
+	// set burnerAcc balance
+	authKeeper.SetModuleAccount(ctx, burnerAcc)
+	suite.
+		Require().
+		NoError(keeper.MintCoins(ctx, authtypes.Minter, totalSupply))
+	suite.
+		Require().
+		NoError(keeper.SendCoinsFromModuleToAccount(ctx, authtypes.Minter, burnerAcc.GetAddress(), totalSupply))
+
+	total, _, err := keeper.GetPaginatedTotalSupply(ctx, &query.PageRequest{})
 	suite.Require().NoError(err)
 	suite.Require().Equal(totalSupply, total)
+
+	// burning all supplied tokens
+	err = keeper.BurnCoins(ctx, authtypes.Burner, totalSupply)
+	suite.Require().NoError(err)
+
+	total, _, err = keeper.GetPaginatedTotalSupply(ctx, &query.PageRequest{})
+	suite.Require().NoError(err)
+	suite.Require().Equal(total.String(), "")
 }
 
 func (suite *IntegrationTestSuite) TestSendCoinsFromModuleToAccount_Blacklist() {
@@ -349,11 +383,15 @@ func (suite *IntegrationTestSuite) TestSendCoinsNewAccount() {
 	app.BankKeeper.GetAllBalances(ctx, addr2)
 	suite.Require().Empty(app.BankKeeper.GetAllBalances(ctx, addr2))
 
-	sendAmt := sdk.NewCoins(newFooCoin(50), newBarCoin(25))
+	sendAmt := sdk.NewCoins(newFooCoin(50), newBarCoin(50))
 	suite.Require().NoError(app.BankKeeper.SendCoins(ctx, addr1, addr2, sendAmt))
 
 	acc2Balances := app.BankKeeper.GetAllBalances(ctx, addr2)
+	acc1Balances = app.BankKeeper.GetAllBalances(ctx, addr1)
 	suite.Require().Equal(sendAmt, acc2Balances)
+	updatedAcc1Bal := balances.Sub(sendAmt)
+	suite.Require().Len(acc1Balances, len(updatedAcc1Bal))
+	suite.Require().Equal(acc1Balances, updatedAcc1Bal)
 	suite.Require().NotNil(app.AccountKeeper.GetAccount(ctx, addr2))
 }
 

x/bank/keeper/send.go

@@ -266,8 +266,13 @@ func (k BaseSendKeeper) setBalance(ctx sdk.Context, addr sdk.AccAddress, balance
 
 	accountStore := k.getAccountStore(ctx, addr)
 
-	bz := k.cdc.MustMarshal(&balance)
-	accountStore.Set([]byte(balance.Denom), bz)
+	// if the balance is zero, we can delete the corresponding denom from the store.
+	if balance.IsZero() {
+		accountStore.Delete([]byte(balance.Denom))
+	} else {
+		bz := k.cdc.MustMarshal(&balance)
+		accountStore.Set([]byte(balance.Denom), bz)
+	}
 
 	return nil
 }