feat: (x/bank) add SpendableCoin method to BaseViewKeeper (#12593)

Author: hallazzang

CHANGELOG.md

@@ -67,6 +67,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking Changes
 
+* (x/bank) [\#12593](https://github.com/cosmos/cosmos-sdk/pull/12593) Add `SpendableCoin` method to `BaseViewKeeper`
 * (x/slashing) [#12581](https://github.com/cosmos/cosmos-sdk/pull/12581) Remove `x/slashing` legacy querier.
 * (types) [\#12355](https://github.com/cosmos/cosmos-sdk/pull/12355) Remove the compile-time `types.DBbackend` variable. Removes usage of the same in server/util.go
 * (x/gov) [#12368](https://github.com/cosmos/cosmos-sdk/pull/12369) Gov keeper is now passed by reference instead of copy to make post-construction mutation of Hooks and Proposal Handlers possible at a framework level.

x/bank/keeper/keeper_test.go

@@ -708,10 +708,12 @@ func (suite *IntegrationTestSuite) TestSpendableCoins() {
 	suite.Require().NoError(testutil.FundAccount(app.BankKeeper, ctx, addr2, origCoins))
 
 	suite.Require().Equal(origCoins, app.BankKeeper.SpendableCoins(ctx, addr2))
+	suite.Require().Equal(origCoins[0], app.BankKeeper.SpendableCoin(ctx, addr2, "stake"))
 
 	ctx = ctx.WithBlockTime(now.Add(12 * time.Hour))
 	suite.Require().NoError(app.BankKeeper.DelegateCoins(ctx, addr2, addrModule, delCoins))
 	suite.Require().Equal(origCoins.Sub(delCoins...), app.BankKeeper.SpendableCoins(ctx, addr1))
+	suite.Require().Equal(origCoins.Sub(delCoins...)[0], app.BankKeeper.SpendableCoin(ctx, addr1, "stake"))
 }
 
 func (suite *IntegrationTestSuite) TestVestingAccountSend() {

x/bank/keeper/view.go

@@ -27,6 +27,7 @@ type ViewKeeper interface {
 	GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin
 	LockedCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins
 	SpendableCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins
+	SpendableCoin(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin
 
 	IterateAccountBalances(ctx sdk.Context, addr sdk.AccAddress, cb func(coin sdk.Coin) (stop bool))
 	IterateAllBalances(ctx sdk.Context, cb func(address sdk.AccAddress, coin sdk.Coin) (stop bool))
@@ -187,6 +188,15 @@ func (k BaseViewKeeper) SpendableCoins(ctx sdk.Context, addr sdk.AccAddress) sdk
 	return spendable
 }
 
+// SpendableCoin returns the balance of specific denomination of spendable coins
+// for an account by address. If the account has no spendable coin, a zero Coin
+// is returned.
+func (k BaseViewKeeper) SpendableCoin(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin {
+	balance := k.GetBalance(ctx, addr, denom)
+	locked := k.LockedCoins(ctx, addr)
+	return balance.SubAmount(locked.AmountOf(denom))
+}
+
 // spendableCoins returns the coins the given address can spend alongside the total amount of coins it holds.
 // It exists for gas efficiency, in order to avoid to have to get balance multiple times.
 func (k BaseViewKeeper) spendableCoins(ctx sdk.Context, addr sdk.AccAddress) (spendable, total sdk.Coins) {

x/bank/spec/02_keepers.md

@@ -140,6 +140,7 @@ type ViewKeeper interface {
     GetBalance(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin
     LockedCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins
     SpendableCoins(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins
+    SpendableCoin(ctx sdk.Context, addr sdk.AccAddress, denom string) sdk.Coin
 
     IterateAccountBalances(ctx sdk.Context, addr sdk.AccAddress, cb func(coin sdk.Coin) (stop bool))
     IterateAllBalances(ctx sdk.Context, cb func(address sdk.AccAddress, coin sdk.Coin) (stop bool))