implement ConversionToAssetBalance in asset-rate

substrate/frame/asset-rate/src/lib.rs

@@ -59,7 +59,10 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use frame_support::traits::{fungible::Inspect, tokens::ConversionFromAssetBalance};
+use frame_support::traits::{
+	fungible::Inspect,
+	tokens::{ConversionFromAssetBalance, ConversionToAssetBalance},
+};
 use sp_runtime::{traits::Zero, FixedPointNumber, FixedU128};
 use sp_std::boxed::Box;
 
@@ -246,3 +249,20 @@ where
 		pallet::ConversionRateToNative::<T>::set(asset_id.clone(), Some(1.into()));
 	}
 }
+
+/// Exposes conversion of a native balance to an asset balance.
+impl<T> ConversionToAssetBalance<BalanceOf<T>, AssetKindOf<T>, BalanceOf<T>> for Pallet<T>
+where
+	T: Config,
+{
+	type Error = pallet::Error<T>;
+
+	fn to_asset_balance(
+		balance: BalanceOf<T>,
+		asset_kind: AssetKindOf<T>,
+	) -> Result<BalanceOf<T>, pallet::Error<T>> {
+		let rate = pallet::ConversionRateToNative::<T>::get(asset_kind)
+			.ok_or(pallet::Error::<T>::UnknownAssetKind.into())?;
+		Ok(FixedU128::from_u32(1).div(rate).saturating_mul_int(balance))
+	}
+}

substrate/frame/asset-rate/src/tests.rs

@@ -131,12 +131,19 @@ fn convert_works() {
 			FixedU128::from_float(2.51)
 		));
 
-		let conversion = <AssetRate as ConversionFromAssetBalance<
+		let conversion_from_asset = <AssetRate as ConversionFromAssetBalance<
 			BalanceOf<Test>,
 			<Test as pallet_asset_rate::Config>::AssetKind,
 			BalanceOf<Test>,
 		>>::from_asset_balance(10, ASSET_ID);
-		assert_eq!(conversion.expect("Conversion rate exists for asset"), 25);
+		assert_eq!(conversion_from_asset.expect("Conversion rate exists for asset"), 25);
+
+		let conversion_to_asset = <AssetRate as ConversionToAssetBalance<
+			BalanceOf<Test>,
+			<Test as pallet_asset_rate::Config>::AssetKind,
+			BalanceOf<Test>,
+		>>::to_asset_balance(25, ASSET_ID);
+		assert_eq!(conversion_to_asset.expect("Conversion rate exists for asset"), 9);
 	});
 }