fix set_balance

Author: zjb0807

tokens/src/lib.rs

@@ -1745,17 +1745,22 @@ impl<T: Config> fungibles::Transfer<T::AccountId> for Pallet<T> {
 impl<T: Config> fungibles::Unbalanced<T::AccountId> for Pallet<T> {
 	fn set_balance(asset_id: Self::AssetId, who: &T::AccountId, amount: Self::Balance) -> DispatchResult {
 		// Balance is the same type and will not overflow
-		Self::mutate_account(who, asset_id, |account, _| {
-			account.free = amount;
+		Self::mutate_account(who, asset_id, |account, _| -> DispatchResult {
+			// fungibles::Unbalanced::decrease_balance didn't check account.reserved
+			// free = new_balance - reserved
+			account.free = amount
+				.checked_sub(&account.reserved)
+				.ok_or(ArithmeticError::Underflow)?;
 
 			Self::deposit_event(Event::BalanceSet {
 				currency_id: asset_id,
 				who: who.clone(),
-				free: amount,
+				free: account.free,
 				reserved: account.reserved,
 			});
-		});
-		Ok(())
+
+			Ok(())
+		})
 	}
 
 	fn set_total_issuance(asset_id: Self::AssetId, amount: Self::Balance) {

tokens/src/tests_events.rs

@@ -202,7 +202,7 @@ fn pallet_fungibles_unbalanced_deposit_events() {
 			System::assert_last_event(Event::Tokens(crate::Event::BalanceSet {
 				currency_id: DOT,
 				who: ALICE,
-				free: 500,
+				free: 450,
 				reserved: 50,
 			}));
 

tokens/src/tests_fungibles.rs

@@ -82,6 +82,23 @@ fn fungibles_unbalanced_trait_should_work() {
 				Ok(5)
 			);
 			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 0);
+			// set reserved
+			assert_ok!(<Tokens as fungibles::Unbalanced<_>>::set_balance(DOT, &ALICE, 100));
+			assert_ok!(<Tokens as MultiReservableCurrency<AccountId>>::reserve(DOT, &ALICE, 50));
+			assert_noop!(
+				<Tokens as fungibles::Unbalanced<_>>::decrease_balance(DOT, &ALICE, 60),
+				ArithmeticError::Underflow
+			);
+			assert_eq!(
+				<Tokens as fungibles::Unbalanced<_>>::decrease_balance(DOT, &ALICE, 50),
+				Ok(50)
+			);
+			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 50);
+			assert_eq!(
+				<Tokens as MultiReservableCurrency<AccountId>>::unreserve(DOT, &ALICE, 50),
+				0
+			);
+			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 50);
 
 			// decrease_balance_at_most
 			assert_ok!(<Tokens as fungibles::Unbalanced<_>>::set_balance(DOT, &ALICE, 10));
@@ -102,8 +119,26 @@ fn fungibles_unbalanced_trait_should_work() {
 				5
 			);
 			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 0);
+			// set reserved
+			assert_ok!(<Tokens as fungibles::Unbalanced<_>>::set_balance(DOT, &ALICE, 100));
+			assert_ok!(<Tokens as MultiReservableCurrency<AccountId>>::reserve(DOT, &ALICE, 50));
+			assert_eq!(
+				<Tokens as fungibles::Unbalanced<_>>::decrease_balance_at_most(DOT, &ALICE, 60),
+				0
+			);
+			assert_eq!(
+				<Tokens as fungibles::Unbalanced<_>>::decrease_balance_at_most(DOT, &ALICE, 50),
+				50
+			);
+			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 50);
+			assert_eq!(
+				<Tokens as MultiReservableCurrency<AccountId>>::unreserve(DOT, &ALICE, 50),
+				0
+			);
+			assert_eq!(<Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE), 50);
 
 			// increase_balance
+			assert_ok!(<Tokens as fungibles::Unbalanced<_>>::set_balance(DOT, &ALICE, 0));
 			assert_noop!(
 				<Tokens as fungibles::Unbalanced<_>>::increase_balance(DOT, &ALICE, 1),
 				TokenError::BelowMinimum