chore: resolve review comments

pallets/nfts/src/benchmarking.rs

@@ -274,7 +274,7 @@ benchmarks_instance_pallet! {
 	mint {
 		let (collection, caller, caller_lookup) = create_collection::<T, I>();
 		let item = T::Helper::item(0);
-		T::Currency::make_free_balance_be(&caller, T::Currency::minimum_balance() + T::CollectionDeposit::get() + T::BalanceDeposit::get());
+		T::Currency::make_free_balance_be(&caller, T::Currency::minimum_balance() + T::CollectionDeposit::get() + T::CollectionBalanceDeposit::get());
 	}: _(SystemOrigin::Signed(caller.clone()), collection, item, caller_lookup, None)
 	verify {
 		assert_last_event::<T, I>(Event::Issued { collection, item, owner: caller }.into());
@@ -283,7 +283,7 @@ benchmarks_instance_pallet! {
 	force_mint {
 		let (collection, caller, caller_lookup) = create_collection::<T, I>();
 		let item = T::Helper::item(0);
-		T::Currency::make_free_balance_be(&caller, T::Currency::minimum_balance() + T::CollectionDeposit::get() + T::BalanceDeposit::get());
+		T::Currency::make_free_balance_be(&caller, T::Currency::minimum_balance() + T::CollectionDeposit::get() + T::CollectionBalanceDeposit::get());
 	}: _(SystemOrigin::Signed(caller.clone()), collection, item, caller_lookup, default_item_config())
 	verify {
 		assert_last_event::<T, I>(Event::Issued { collection, item, owner: caller }.into());
@@ -303,7 +303,7 @@ benchmarks_instance_pallet! {
 
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
-		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance() + T::BalanceDeposit::get());
+		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance() + T::CollectionBalanceDeposit::get());
 	}: _(SystemOrigin::Signed(caller.clone()), collection, item, target_lookup)
 	verify {
 		assert_last_event::<T, I>(Event::Transferred { collection, item, from: caller, to: target }.into());
@@ -669,7 +669,7 @@ benchmarks_instance_pallet! {
 		let price = ItemPrice::<T, I>::from(0u32);
 		let origin = SystemOrigin::Signed(seller.clone()).into();
 		Nfts::<T, I>::set_price(origin, collection, item, Some(price), Some(buyer_lookup))?;
-		T::Currency::make_free_balance_be(&buyer, T::Currency::minimum_balance() + price + T::BalanceDeposit::get());
+		T::Currency::make_free_balance_be(&buyer, T::Currency::minimum_balance() + price + T::CollectionBalanceDeposit::get());
 	}: _(SystemOrigin::Signed(buyer.clone()), collection, item, price)
 	verify {
 		assert_last_event::<T, I>(Event::ItemBought {
@@ -759,7 +759,7 @@ benchmarks_instance_pallet! {
 		let duration = T::MaxDeadlineDuration::get();
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
-		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance() + T::BalanceDeposit::get());
+		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance() + T::CollectionBalanceDeposit::get());
 		let origin = SystemOrigin::Signed(caller.clone());
 		frame_system::Pallet::<T>::set_block_number(One::one());
 		Nfts::<T, I>::transfer(origin.clone().into(), collection, item2, target_lookup)?;

pallets/nfts/src/common_functions.rs

@@ -129,7 +129,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 					maybe_balance.as_mut().ok_or(Error::<T, I>::NoItemOwned)?;
 
 				*balance = balance.checked_sub(1).ok_or(ArithmeticError::Underflow)?;
-				if *balance == 0 {
+				if balance.is_zero() {
 					T::Currency::unreserve(deposit_account, *deposit_amount);
 					*maybe_balance = None;
 				}

pallets/nfts/src/features/approvals.rs

@@ -218,7 +218,7 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		);
 		ensure!(
 			AccountBalance::<T, I>::get(collection, &owner)
-				.filter(|(balance, _)| *balance > 0)
+				.filter(|(balance, _)| !balance.is_zero())
 				.is_some(),
 			Error::<T, I>::NoItemOwned
 		);

pallets/nfts/src/features/create_delete_item.rs

@@ -74,8 +74,9 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 			let deposit_account =
 				maybe_depositor.unwrap_or_else(|| collection_details.owner.clone());
 
-			let balance_deposit =
-				deposit_required.then_some(T::BalanceDeposit::get()).unwrap_or_default();
+			let balance_deposit = deposit_required
+				.then_some(T::CollectionBalanceDeposit::get())
+				.unwrap_or_default();
 			Self::increment_account_balance(
 				collection,
 				&mint_to,

pallets/nfts/src/features/transfer.rs

@@ -94,15 +94,16 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		// Update account balance of the destination account.
 		let deposit_amount =
 			match collection_config.is_setting_enabled(CollectionSetting::DepositRequired) {
-				true => T::BalanceDeposit::get(),
+				true => T::CollectionBalanceDeposit::get(),
 				false => Zero::zero(),
 			};
-		// The destination account covers the `BalanceDeposit` if it has sufficient balance.
-		// Otherwise, the caller is accountable for it.
-		let deposit_account = match T::Currency::can_reserve(&dest, T::BalanceDeposit::get()) {
-			true => &dest,
-			false => caller,
-		};
+		// The destination account covers the `CollectionBalanceDeposit` if it has sufficient
+		// balance. Otherwise, the caller is accountable for it.
+		let deposit_account =
+			match T::Currency::can_reserve(&dest, T::CollectionBalanceDeposit::get()) {
+				true => &dest,
+				false => caller,
+			};
 
 		Self::increment_account_balance(collection, &dest, (deposit_account, deposit_amount))?;
 

pallets/nfts/src/lib.rs

@@ -260,11 +260,11 @@ pub mod pallet {
 		#[pallet::constant]
 		type CollectionApprovalDeposit: Get<DepositBalanceOf<Self, I>>;
 
-		/// The basic amount of funds that must be reversed for an account balance.
+		/// The basic amount of funds that must be reversed for an account's collection balance.
 		// Key: `sizeof((CollectionId, AccountId))` bytes.
 		// Value: `sizeof((u32, Some(AccountId, Balance)))` bytes.
 		#[pallet::constant]
-		type BalanceDeposit: Get<DepositBalanceOf<Self, I>>;
+		type CollectionBalanceDeposit: Get<DepositBalanceOf<Self, I>>;
 	}
 
 	/// Details of a collection.
@@ -441,6 +441,7 @@ pub mod pallet {
 		T::CollectionId,
 		Blake2_128Concat,
 		T::AccountId,
+		// (Account's collection items, Deposit details).
 		(u32, AccountDepositOf<T, I>),
 	>;
 

pallets/nfts/src/mock.rs

@@ -65,8 +65,8 @@ parameter_types! {
 impl Config for Test {
 	type ApprovalsLimit = ConstU32<10>;
 	type AttributeDepositBase = ConstU64<1>;
-	type BalanceDeposit = ConstU64<1>;
 	type CollectionApprovalDeposit = ConstU64<1>;
+	type CollectionBalanceDeposit = ConstU64<1>;
 	type CollectionDeposit = ConstU64<2>;
 	type CollectionId = u32;
 	type CreateOrigin = AsEnsureOriginWithArg<frame_system::EnsureSigned<Self::AccountId>>;

pallets/nfts/src/tests.rs

@@ -214,7 +214,7 @@ fn cancel_collection_approval(
 }
 
 fn balance_deposit() -> DepositBalanceOf<Test> {
-	<<Test as Config>::BalanceDeposit>::get()
+	<<Test as Config>::CollectionBalanceDeposit>::get()
 }
 
 #[test]

runtime/devnet/src/config/assets.rs

@@ -30,7 +30,7 @@ parameter_types! {
 parameter_types! {
 	pub NftsPalletFeatures: PalletFeatures = PalletFeatures::all_enabled();
 	// Key = 68 bytes (4+16+32+16), Value = 52 bytes (4+32+16)
-	pub const NftsBalanceDeposit: Balance = deposit(1, 120);
+	pub const NftsCollectionBalanceDeposit: Balance = deposit(1, 120);
 	pub const NftsCollectionDeposit: Balance = 10 * UNIT;
 	// Key = 116 bytes (4+16+32+16+32+16), Value = 21 bytes (1+4+16)
 	pub const NftsCollectionApprovalDeposit: Balance = deposit(1, 137);
@@ -45,8 +45,8 @@ impl pallet_nfts::Config for Runtime {
 	// TODO: source from primitives
 	type ApprovalsLimit = ConstU32<20>;
 	type AttributeDepositBase = NftsAttributeDepositBase;
-	type BalanceDeposit = NftsBalanceDeposit;
 	type CollectionApprovalDeposit = NftsCollectionApprovalDeposit;
+	type CollectionBalanceDeposit = NftsCollectionBalanceDeposit;
 	type CollectionDeposit = NftsCollectionDeposit;
 	// TODO: source from primitives
 	type CollectionId = CollectionId;
@@ -139,7 +139,7 @@ mod tests {
 			.first()
 			.and_then(|info| info.max_size)
 			.unwrap_or_default();
-		assert_eq!(deposit(1, max_size), NftsBalanceDeposit::get());
+		assert_eq!(deposit(1, max_size), NftsCollectionBalanceDeposit::get());
 	}
 
 	#[test]

runtime/testnet/src/config/assets.rs

@@ -30,7 +30,7 @@ parameter_types! {
 parameter_types! {
 	pub NftsPalletFeatures: PalletFeatures = PalletFeatures::all_enabled();
 	// Key = 68 bytes (4+16+32+16), Value = 52 bytes (4+32+16)
-	pub const NftsBalanceDeposit: Balance = deposit(1, 120);
+	pub const NftsCollectionBalanceDeposit: Balance = deposit(1, 120);
 	pub const NftsCollectionDeposit: Balance = 10 * UNIT;
 	// Key = 116 bytes (4+16+32+16+32+16), Value = 21 bytes (1+4+16)
 	pub const NftsCollectionApprovalDeposit: Balance = deposit(1, 137);
@@ -45,8 +45,8 @@ impl pallet_nfts::Config for Runtime {
 	// TODO: source from primitives
 	type ApprovalsLimit = ConstU32<20>;
 	type AttributeDepositBase = NftsAttributeDepositBase;
-	type BalanceDeposit = NftsBalanceDeposit;
 	type CollectionApprovalDeposit = NftsCollectionApprovalDeposit;
+	type CollectionBalanceDeposit = NftsCollectionBalanceDeposit;
 	type CollectionDeposit = NftsCollectionDeposit;
 	// TODO: source from primitives
 	type CollectionId = CollectionId;
@@ -139,7 +139,7 @@ mod tests {
 			.first()
 			.and_then(|info| info.max_size)
 			.unwrap_or_default();
-		assert_eq!(deposit(1, max_size), NftsBalanceDeposit::get());
+		assert_eq!(deposit(1, max_size), NftsCollectionBalanceDeposit::get());
 	}
 
 	#[test]