update asset_exists (#866)

tokens/src/impls.rs

@@ -68,8 +68,12 @@ where
 		}
 	}
 
-	fn asset_exists(_asset: Self::AssetId) -> bool {
-		false
+	fn asset_exists(asset: Self::AssetId) -> bool {
+		if TestKey::contains(&asset) {
+			true
+		} else {
+			B::asset_exists(asset)
+		}
 	}
 }
 

tokens/src/lib.rs

@@ -1750,8 +1750,8 @@ impl<T: Config> fungibles::Inspect<T::AccountId> for Pallet<T> {
 		Self::withdraw_consequence(who, asset_id, amount, &Self::accounts(who, asset_id))
 	}
 
-	fn asset_exists(_asset: Self::AssetId) -> bool {
-		false
+	fn asset_exists(asset: Self::AssetId) -> bool {
+		TotalIssuance::<T>::contains_key(asset)
 	}
 }
 

tokens/src/tests_fungibles.rs

@@ -22,6 +22,9 @@ fn fungibles_inspect_trait_should_work() {
 			);
 			assert_ok!(<Tokens as fungibles::Inspect<_>>::can_deposit(DOT, &ALICE, 1, false).into_result());
 			assert_ok!(<Tokens as fungibles::Inspect<_>>::can_withdraw(DOT, &ALICE, 1).into_result());
+
+			assert!(<Tokens as fungibles::Inspect<_>>::asset_exists(DOT));
+			assert!(!<Tokens as fungibles::Inspect<_>>::asset_exists(BTC));
 		});
 }
 
@@ -283,7 +286,7 @@ fn fungibles_inspect_convert_should_work() {
 	>;
 
 	ExtBuilder::default()
-		.balances(vec![(ALICE, DOT, 100), (BOB, DOT, 100)])
+		.balances(vec![(ALICE, DOT, 100), (BOB, DOT, 100), (BOB, BTC, 100)])
 		.build()
 		.execute_with(|| {
 			assert_eq!(
@@ -294,6 +297,10 @@ fn fungibles_inspect_convert_should_work() {
 				<RebaseTokens as fungibles::Inspect<AccountId>>::total_issuance(DOT),
 				20000
 			);
+
+			assert!(<Tokens as fungibles::Inspect<_>>::asset_exists(DOT));
+			assert!(<Tokens as fungibles::Inspect<_>>::asset_exists(BTC));
+			assert!(!<Tokens as fungibles::Inspect<_>>::asset_exists(ETH));
 		});
 }