Implement necessary Balanced types

tokens/src/lib.rs

@@ -358,6 +358,14 @@ pub mod module {
 			who: T::AccountId,
 			amount: T::Balance,
 		},
+		Issued {
+			currency_id: T::CurrencyId,
+			amount: T::Balance,
+		},
+		Rescinded {
+			currency_id: T::CurrencyId,
+			amount: T::Balance,
+		},
 	}
 
 	/// The total issuance of a token type.
@@ -1928,6 +1936,32 @@ impl<T: Config> fungibles::Unbalanced<T::AccountId> for Pallet<T> {
 	}
 }
 
+impl<T: Config> fungibles::Balanced<T::AccountId> for Pallet<T> {
+	type OnDropDebt = fungibles::IncreaseIssuance<T::AccountId, Self>;
+	type OnDropCredit = fungibles::DecreaseIssuance<T::AccountId, Self>;
+
+	fn done_deposit(currency_id: Self::AssetId, who: &T::AccountId, amount: Self::Balance) {
+		Self::deposit_event(Event::Deposited {
+			currency_id,
+			who: who.clone(),
+			amount,
+		});
+	}
+	fn done_withdraw(currency_id: Self::AssetId, who: &T::AccountId, amount: Self::Balance) {
+		Self::deposit_event(Event::Withdrawn {
+			currency_id,
+			who: who.clone(),
+			amount,
+		});
+	}
+	fn done_issue(currency_id: Self::AssetId, amount: Self::Balance) {
+		Self::deposit_event(Event::Issued { currency_id, amount });
+	}
+	fn done_rescind(currency_id: Self::AssetId, amount: Self::Balance) {
+		Self::deposit_event(Event::Rescinded { currency_id, amount });
+	}
+}
+
 type ReasonOf<P, T> = <P as fungibles::InspectHold<<T as frame_system::Config>::AccountId>>::Reason;
 impl<T: Config> fungibles::InspectHold<T::AccountId> for Pallet<T> {
 	type Reason = ();

tokens/src/tests_fungibles.rs

@@ -287,6 +287,102 @@ fn fungibles_unbalanced_trait_should_work() {
 		});
 }
 
+#[test]
+fn fungibles_balanced_deposit_works() {
+	ExtBuilder::default()
+		.balances(vec![(ALICE, DOT, 100)])
+		.build()
+		.execute_with(|| {
+			let amount = 42;
+			let alice_old_balance = <Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE);
+			let debt = <Tokens as fungibles::Balanced<_>>::deposit(DOT, &ALICE, amount, Precision::Exact).unwrap();
+			assert_eq!(debt.asset(), DOT);
+			assert_eq!(debt.peek(), amount);
+			let alice_new_balance = <Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE);
+			assert_eq!(alice_old_balance + amount, alice_new_balance);
+
+			System::assert_last_event(RuntimeEvent::Tokens(crate::Event::Deposited {
+				currency_id: DOT,
+				who: ALICE,
+				amount,
+			}));
+		});
+}
+
+#[test]
+fn fungibles_balanced_withdraw_works() {
+	ExtBuilder::default()
+		.balances(vec![(ALICE, DOT, 100)])
+		.build()
+		.execute_with(|| {
+			let amount = 42;
+			let alice_old_balance = <Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE);
+			let credit = <Tokens as fungibles::Balanced<_>>::withdraw(
+				DOT,
+				&ALICE,
+				amount,
+				Precision::Exact,
+				Preservation::Protect,
+				Fortitude::Polite,
+			)
+			.unwrap();
+			assert_eq!(credit.asset(), DOT);
+			assert_eq!(credit.peek(), amount);
+			let alice_new_balance = <Tokens as fungibles::Inspect<_>>::balance(DOT, &ALICE);
+			assert_eq!(alice_old_balance - amount, alice_new_balance);
+
+			System::assert_last_event(RuntimeEvent::Tokens(crate::Event::Withdrawn {
+				currency_id: DOT,
+				who: ALICE,
+				amount,
+			}));
+		});
+}
+
+#[test]
+fn fungibles_balanced_issue_works() {
+	ExtBuilder::default()
+		.balances(vec![(ALICE, DOT, 100)])
+		.build()
+		.execute_with(|| {
+			let amount = 42;
+
+			let old_total_issuance = <Tokens as fungibles::Inspect<_>>::total_issuance(DOT);
+			let credit = <Tokens as fungibles::Balanced<_>>::issue(DOT, amount);
+			assert_eq!(credit.asset(), DOT);
+			assert_eq!(credit.peek(), amount);
+			let new_total_issuance = <Tokens as fungibles::Inspect<_>>::total_issuance(DOT);
+			assert_eq!(old_total_issuance + amount, new_total_issuance);
+
+			System::assert_last_event(RuntimeEvent::Tokens(crate::Event::Issued {
+				currency_id: DOT,
+				amount,
+			}));
+		});
+}
+
+#[test]
+fn fungibles_balanced_rescind_works() {
+	ExtBuilder::default()
+		.balances(vec![(ALICE, DOT, 100)])
+		.build()
+		.execute_with(|| {
+			let amount = 42;
+
+			let old_total_issuance = <Tokens as fungibles::Inspect<_>>::total_issuance(DOT);
+			let debt = <Tokens as fungibles::Balanced<_>>::rescind(DOT, amount);
+			assert_eq!(debt.asset(), DOT);
+			assert_eq!(debt.peek(), amount);
+			let new_total_issuance = <Tokens as fungibles::Inspect<_>>::total_issuance(DOT);
+			assert_eq!(old_total_issuance - amount, new_total_issuance);
+
+			System::assert_last_event(RuntimeEvent::Tokens(crate::Event::Rescinded {
+				currency_id: DOT,
+				amount,
+			}));
+		});
+}
+
 #[test]
 fn fungibles_inspect_hold_trait_should_work() {
 	ExtBuilder::default()