Assets pallet: Giving the asset owner the ability to set minimum bala…

…nce (#13486)

* set_min_balance

* allow when new_min_balance < old_min_balance

* add more specific event

* Update frame/assets/src/lib.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

* Update frame/assets/src/lib.rs

Co-authored-by: Bastian Köcher <git@kchr.de>

* ".git/.scripts/commands/bench/bench.sh" pallet dev pallet_assets

* use actual weight

---------

Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: command-bot <>

frame/assets/src/benchmarking.rs

@@ -471,5 +471,12 @@ benchmarks_instance_pallet! {
  assert_last_event::<T, I>(Event::ApprovalCancelled { asset_id: asset_id.into(), owner: caller, delegate }.into());
  }
 
+ set_min_balance {
+ let (asset_id, caller, caller_lookup) = create_default_asset::<T, I>(true);
+ }: _(SystemOrigin::Signed(caller.clone()), asset_id, 50u32.into())
+ verify {
+ assert_last_event::<T, I>(Event::AssetMinBalanceChanged { asset_id: asset_id.into(), new_min_balance: 50u32.into() }.into());
+ }
+
  impl_benchmark_test_suite!(Assets, crate::mock::new_test_ext(), crate::mock::Test)
 }

frame/assets/src/lib.rs

@@ -514,6 +514,8 @@ pub mod pallet {
  },
  /// An asset has had its attributes changed by the `Force` origin.
  AssetStatusChanged { asset_id: T::AssetId },
+ /// The min_balance of an asset has been updated by the asset owner.
+ AssetMinBalanceChanged { asset_id: T::AssetId, new_min_balance: T::Balance },
  }
 
  #[pallet::error]
@@ -1511,6 +1513,49 @@ pub mod pallet {
  let id: T::AssetId = id.into();
  Self::do_refund(id, ensure_signed(origin)?, allow_burn)
  }
+
+ /// Sets the minimum balance of an asset.
+ ///
+ /// Only works if there aren't any accounts that are holding the asset or if
+ /// the new value of `min_balance` is less than the old one.
+ ///
+ /// Origin must be Signed and the sender has to be the Owner of the
+ /// asset `id`.
+ ///
+ /// - `id`: The identifier of the asset.
+ /// - `min_balance`: The new value of `min_balance`.
+ ///
+ /// Emits `AssetMinBalanceChanged` event when successful.
+ #[pallet::call_index(28)]
+ #[pallet::weight(T::WeightInfo::set_min_balance())]
+ pub fn set_min_balance(
+ origin: OriginFor<T>,
+ id: T::AssetIdParameter,
+ min_balance: T::Balance,
+ ) -> DispatchResult {
+ let origin = ensure_signed(origin)?;
+ let id: T::AssetId = id.into();
+
+ let mut details = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+ ensure!(origin == details.owner, Error::<T, I>::NoPermission);
+
+ let old_min_balance = details.min_balance;
+ // Ensure that either the new min_balance is less than old min_balance or there aren't
+ // any accounts holding the asset.
+ ensure!(
+ min_balance < old_min_balance || details.accounts == 0,
+ Error::<T, I>::NoPermission
+ );
+
+ details.min_balance = min_balance;
+ Asset::<T, I>::insert(&id, details);
+
+ Self::deposit_event(Event::AssetMinBalanceChanged {
+ asset_id: id,
+ new_min_balance: min_balance,
+ });
+ Ok(())
+ }
  }
 }
 

frame/assets/src/tests.rs

@@ -1091,6 +1091,35 @@ fn force_asset_status_should_work() {
  });
 }
 
+#[test]
+fn set_min_balance_should_work() {
+ new_test_ext().execute_with(|| {
+ let id = 42;
+ Balances::make_free_balance_be(&1, 10);
+ assert_ok!(Assets::create(RuntimeOrigin::signed(1), id, 1, 30));
+
+ assert_ok!(Assets::mint(RuntimeOrigin::signed(1), id, 1, 50));
+ // won't execute because there is an asset holder.
+ assert_noop!(
+ Assets::set_min_balance(RuntimeOrigin::signed(1), id, 50),
+ Error::<Test>::NoPermission
+ );
+
+ // will execute because the new value of min_balance is less than the
+ // old value. 10 < 30
+ assert_ok!(Assets::mint(RuntimeOrigin::signed(1), id, 1, 10));
+
+ assert_ok!(Assets::burn(RuntimeOrigin::signed(1), id, 1, 50));
+ assert_noop!(
+ Assets::set_min_balance(RuntimeOrigin::signed(2), id, 50),
+ Error::<Test>::NoPermission
+ );
+
+ assert_ok!(Assets::set_min_balance(RuntimeOrigin::signed(1), id, 50));
+ assert_eq!(Asset::<Test>::get(id).unwrap().min_balance, 50);
+ });
+}
+
 #[test]
 fn balance_conversion_should_work() {
  new_test_ext().execute_with(|| {