Cherry-pick the upstream feature "Staking Payout to Any Account" (#137)

* Support Staking Payout to Any Account (#6832)

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

frame/staking/src/lib.rs

@@ -334,16 +334,18 @@ pub enum StakerStatus<AccountId> {
 
 /// A destination account for payment.
 #[derive(PartialEq, Eq, Copy, Clone, Encode, Decode, RuntimeDebug)]
-pub enum RewardDestination {
+pub enum RewardDestination<AccountId> {
 	/// Pay into the stash account, increasing the amount at stake accordingly.
 	Staked,
 	/// Pay into the stash account, not increasing the amount at stake.
 	Stash,
 	/// Pay into the controller account.
 	Controller,
+	/// Pay into a specified account.
+	Account(AccountId),
 }
 
-impl Default for RewardDestination {
+impl<AccountId> Default for RewardDestination<AccountId> {
 	fn default() -> Self {
 		RewardDestination::Staked
 	}
@@ -725,7 +727,7 @@ decl_storage! {
 			=> Option<StakingLedger<T::AccountId, BalanceOf<T>>>;
 
 		/// Where the reward payment should be made. Keyed by stash.
-		pub Payee get(fn payee): map hasher(twox_64_concat) T::AccountId => RewardDestination;
+		pub Payee get(fn payee): map hasher(twox_64_concat) T::AccountId => RewardDestination<T::AccountId>;
 
 		/// The map from (wannabe) validator stash key to the preferences of that validator.
 		pub Validators get(fn validators):
@@ -993,7 +995,7 @@ decl_module! {
 		fn bond(origin,
 			controller: <T::Lookup as StaticLookup>::Source,
 			#[compact] value: BalanceOf<T>,
-			payee: RewardDestination
+			payee: RewardDestination<T::AccountId>,
 		) {
 			let stash = ensure_signed(origin)?;
 
@@ -1249,7 +1251,7 @@ decl_module! {
 		/// - Writes are limited to the `origin` account key.
 		/// # </weight>
 		#[weight = SimpleDispatchInfo::FixedNormal(500_000)]
-		fn set_payee(origin, payee: RewardDestination) {
+		fn set_payee(origin, payee: RewardDestination<T::AccountId>) {
 			let controller = ensure_signed(origin)?;
 			let ledger = Self::ledger(&controller).ok_or(Error::<T>::NotController)?;
 			let stash = &ledger.stash;
@@ -1636,6 +1638,9 @@ impl<T: Trait> Module<T> {
 					Self::update_ledger(&controller, &l);
 					r
 				}),
+			RewardDestination::Account(dest_account) => {
+				Some(T::Currency::deposit_creating(&dest_account, amount))
+			}
 		}
 	}
 

frame/staking/src/mock.rs

@@ -235,7 +235,7 @@ pub struct ExtBuilder {
 	fair: bool,
 	num_validators: Option<u32>,
 	invulnerables: Vec<u64>,
-	stakers: bool,
+	has_stakers: bool,
 }
 
 impl Default for ExtBuilder {
@@ -250,7 +250,7 @@ impl Default for ExtBuilder {
 			fair: true,
 			num_validators: None,
 			invulnerables: vec![],
-			stakers: true,
+			has_stakers: true,
 		}
 	}
 }
@@ -296,11 +296,8 @@ impl ExtBuilder {
 		EXISTENTIAL_DEPOSIT.with(|v| *v.borrow_mut() = self.existential_deposit);
 		SLASH_DEFER_DURATION.with(|v| *v.borrow_mut() = self.slash_defer_duration);
 	}
-
-	// TODO re-evaluate if the following "allow" is still necessary after merging upstream in
-	#[allow(dead_code)]
-	pub fn stakers(mut self, has_stakers: bool) -> Self {
-		self.stakers = has_stakers;
+	pub fn has_stakers(mut self, has: bool) -> Self {
+		self.has_stakers = has;
 		self
 	}
 	pub fn build(self) -> sp_io::TestExternalities {
@@ -339,7 +336,7 @@ impl ExtBuilder {
 		}.assimilate_storage(&mut storage);
 
 		let mut stakers = vec![];
-		if self.stakers {
+		if self.has_stakers {
 			let stake_21 = if self.fair { 1000 } else { 2000 };
 			let stake_31 = if self.validator_pool { balance_factor * 1000 } else { 1 };
 			let status_41 = if self.validator_pool {
@@ -444,20 +441,36 @@ pub fn assert_ledger_consistent(stash: AccountId) {
 	assert_eq!(real_total, ledger.total);
 }
 
-pub fn bond_validator(acc: u64, val: u64) {
-	// a = controller
-	// a + 1 = stash
-	let _ = Balances::make_free_balance_be(&(acc + 1), val);
-	assert_ok!(Staking::bond(Origin::signed(acc + 1), acc, val, RewardDestination::Controller));
-	assert_ok!(Staking::validate(Origin::signed(acc), ValidatorPrefs::default()));
-}
-
-pub fn bond_nominator(acc: u64, val: u64, target: Vec<u64>) {
-	// a = controller
-	// a + 1 = stash
-	let _ = Balances::make_free_balance_be(&(acc + 1), val);
-	assert_ok!(Staking::bond(Origin::signed(acc + 1), acc, val, RewardDestination::Controller));
-	assert_ok!(Staking::nominate(Origin::signed(acc), target));
+pub(crate) fn bond_validator(stash: AccountId, ctrl: AccountId, val: Balance) {
+	let _ = Balances::make_free_balance_be(&stash, val);
+	let _ = Balances::make_free_balance_be(&ctrl, val);
+	assert_ok!(Staking::bond(
+		Origin::signed(stash),
+		ctrl,
+		val,
+		RewardDestination::Controller,
+	));
+	assert_ok!(Staking::validate(
+		Origin::signed(ctrl),
+		ValidatorPrefs::default()
+	));
+}
+
+pub(crate) fn bond_nominator(
+	stash: AccountId,
+	ctrl: AccountId,
+	val: Balance,
+	target: Vec<AccountId>,
+) {
+	let _ = Balances::make_free_balance_be(&stash, val);
+	let _ = Balances::make_free_balance_be(&ctrl, val);
+	assert_ok!(Staking::bond(
+		Origin::signed(stash),
+		ctrl,
+		val,
+		RewardDestination::Controller,
+	));
+	assert_ok!(Staking::nominate(Origin::signed(ctrl), target));
 }
 
 pub fn advance_session() {

frame/staking/src/tests.rs

@@ -1733,11 +1733,11 @@ fn phragmen_should_not_overflow_validators() {
 		let _ = Staking::chill(Origin::signed(10));
 		let _ = Staking::chill(Origin::signed(20));
 
-		bond_validator(2, u64::max_value());
-		bond_validator(4, u64::max_value());
+		bond_validator(3, 2, u64::max_value());
+		bond_validator(5, 4, u64::max_value());
 
-		bond_nominator(6, u64::max_value() / 2, vec![3, 5]);
-		bond_nominator(8, u64::max_value() / 2, vec![3, 5]);
+		bond_nominator(7, 6, u64::max_value() / 2, vec![3, 5]);
+		bond_nominator(9, 8, u64::max_value() / 2, vec![3, 5]);
 
 		start_era(1);
 
@@ -1756,11 +1756,11 @@ fn phragmen_should_not_overflow_nominators() {
 		let _ = Staking::chill(Origin::signed(10));
 		let _ = Staking::chill(Origin::signed(20));
 
-		bond_validator(2, u64::max_value() / 2);
-		bond_validator(4, u64::max_value() / 2);
+		bond_validator(3, 2, u64::max_value() / 2);
+		bond_validator(5, 4, u64::max_value() / 2);
 
-		bond_nominator(6, u64::max_value(), vec![3, 5]);
-		bond_nominator(8, u64::max_value(), vec![3, 5]);
+		bond_nominator(7, 6, u64::max_value(), vec![3, 5]);
+		bond_nominator(9, 8, u64::max_value(), vec![3, 5]);
 
 		start_era(1);
 
@@ -1775,11 +1775,11 @@ fn phragmen_should_not_overflow_nominators() {
 #[test]
 fn phragmen_should_not_overflow_ultimate() {
 	ExtBuilder::default().nominate(false).build().execute_with(|| {
-		bond_validator(2, u64::max_value());
-		bond_validator(4, u64::max_value());
+		bond_validator(3, 2, u64::max_value());
+		bond_validator(5, 4, u64::max_value());
 
-		bond_nominator(6, u64::max_value(), vec![3, 5]);
-		bond_nominator(8, u64::max_value(), vec![3, 5]);
+		bond_nominator(7, 6, u64::max_value(), vec![3, 5]);
+		bond_nominator(9, 8, u64::max_value(), vec![3, 5]);
 
 		start_era(1);
 
@@ -3043,3 +3043,32 @@ fn assert_migration_is_noop() {
 	assert_eq!(era.index, 586);
 	assert_eq!(era.start, Some(1585135674000));
 }
+
+#[test]
+fn payout_to_any_account_works() {
+	ExtBuilder::default().has_stakers(false).build().execute_with(|| {
+		let balance = 1000;
+		// Create a validator:
+		bond_validator(11, 10, balance); // Default(64)
+
+		// Create a stash/controller pair
+		bond_nominator(1234, 1337, 100, vec![11]);
+
+		// Update payout location
+		assert_ok!(Staking::set_payee(Origin::signed(1337), RewardDestination::Account(42)));
+
+		// Reward Destination account doesn't exist
+		assert_eq!(Balances::free_balance(42), 0);
+
+		mock::start_era(1);
+		Staking::reward_by_ids(vec![(11, 1)]);
+		// Compute total payout now for whole duration as other parameter won't change
+		let total_payout_0 = current_total_payout_for_duration(3 * 1000);
+		assert!(total_payout_0 > 100); // Test is meaningful if reward something
+		mock::start_era(2);
+		assert_ok!(Staking::payout_nominator(Origin::signed(1337), 1, vec![(11, 0)]));
+
+		// Payment is successful
+		assert!(Balances::free_balance(42) > 0);
+	})
+}