Various minor fixes (#13945)

* Fix: Incorrect implementation of can_reserve check

* Fix: Incorrect migration of consumer counting for existing accounts with frozen amounts

* Fix: Inconsistent implementation between assets can_deposit and new_account

* Fixes

* Fixes

* Another fix

* Update tests.rs

* Update fungible_tests.rs

* Use `can_accrue_consumers` in the body of `can_inc_consumer`

---------

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: parity-processbot <>

substrate/frame/balances/src/tests/currency_tests.rs

@@ -1180,6 +1180,16 @@ fn named_reserve_should_work() {
 	});
 }
 
+#[test]
+fn reserve_must_succeed_if_can_reserve_does() {
+	ExtBuilder::default().build_and_execute_with(|| {
+		let _ = Balances::deposit_creating(&1, 1);
+		let _ = Balances::deposit_creating(&2, 2);
+		assert!(Balances::can_reserve(&1, 1) == Balances::reserve(&1, 1).is_ok());
+		assert!(Balances::can_reserve(&2, 1) == Balances::reserve(&2, 1).is_ok());
+	});
+}
+
 #[test]
 fn reserved_named_to_yourself_should_work() {
 	ExtBuilder::default().build_and_execute_with(|| {

substrate/frame/balances/src/tests/fungible_tests.rs

@@ -398,6 +398,31 @@ fn unholding_frees_hold_slot() {
 		});
 }
 
+#[test]
+fn sufficients_work_properly_with_reference_counting() {
+	ExtBuilder::default()
+		.existential_deposit(1)
+		.monied(true)
+		.build_and_execute_with(|| {
+			// Only run PoC when the system pallet is enabled, since the underlying bug is in the
+			// system pallet it won't work with BalancesAccountStore
+			if UseSystem::get() {
+				// Start with a balance of 100
+				<Balances as fungible::Mutate<_>>::set_balance(&1, 100);
+				// Emulate a sufficient, in reality this could be reached by transferring a
+				// sufficient asset to the account
+				System::inc_sufficients(&1);
+				// Spend the same balance multiple times
+				assert_ok!(<Balances as fungible::Mutate<_>>::transfer(&1, &1337, 100, Expendable));
+				assert_eq!(Balances::free_balance(&1), 0);
+				assert_noop!(
+					<Balances as fungible::Mutate<_>>::transfer(&1, &1337, 100, Expendable),
+					TokenError::FundsUnavailable
+				);
+			}
+		});
+}
+
 #[test]
 fn emit_events_with_changing_freezes() {
 	ExtBuilder::default().build_and_execute_with(|| {