OpenGov: Abstentions (paritytech#12842)

* OpenGov: Abstentions

* Tests

frame/conviction-voting/src/tests.rs

@@ -237,6 +237,14 @@ fn nay(amount: u64, conviction: u8) -> AccountVote<u64> {
 	AccountVote::Standard { vote, balance: amount }
 }
 
+fn split(aye: u64, nay: u64) -> AccountVote<u64> {
+	AccountVote::Split { aye, nay }
+}
+
+fn split_abstain(aye: u64, nay: u64, abstain: u64) -> AccountVote<u64> {
+	AccountVote::SplitAbstain { aye, nay, abstain }
+}
+
 fn tally(index: u8) -> TallyOf<Test> {
 	<TestPolls as Polling<TallyOf<Test>>>::as_ongoing(index).expect("No poll").0
 }
@@ -295,6 +303,49 @@ fn basic_voting_works() {
 	});
 }
 
+#[test]
+fn split_voting_works() {
+	new_test_ext().execute_with(|| {
+		assert_ok!(Voting::vote(RuntimeOrigin::signed(1), 3, split(10, 0)));
+		assert_eq!(tally(3), Tally::from_parts(1, 0, 10));
+		assert_ok!(Voting::vote(RuntimeOrigin::signed(1), 3, split(5, 5)));
+		assert_eq!(tally(3), Tally::from_parts(0, 0, 5));
+		assert_eq!(Balances::usable_balance(1), 0);
+
+		assert_ok!(Voting::remove_vote(RuntimeOrigin::signed(1), None, 3));
+		assert_eq!(tally(3), Tally::from_parts(0, 0, 0));
+
+		assert_ok!(Voting::unlock(RuntimeOrigin::signed(1), class(3), 1));
+		assert_eq!(Balances::usable_balance(1), 10);
+	});
+}
+
+#[test]
+fn abstain_voting_works() {
+	new_test_ext().execute_with(|| {
+		assert_ok!(Voting::vote(RuntimeOrigin::signed(1), 3, split_abstain(0, 0, 10)));
+		assert_eq!(tally(3), Tally::from_parts(0, 0, 10));
+		assert_ok!(Voting::vote(RuntimeOrigin::signed(2), 3, split_abstain(0, 0, 20)));
+		assert_eq!(tally(3), Tally::from_parts(0, 0, 30));
+		assert_ok!(Voting::vote(RuntimeOrigin::signed(2), 3, split_abstain(10, 0, 10)));
+		assert_eq!(tally(3), Tally::from_parts(1, 0, 30));
+		assert_eq!(Balances::usable_balance(1), 0);
+		assert_eq!(Balances::usable_balance(2), 0);
+
+		assert_ok!(Voting::remove_vote(RuntimeOrigin::signed(1), None, 3));
+		assert_eq!(tally(3), Tally::from_parts(1, 0, 20));
+
+		assert_ok!(Voting::remove_vote(RuntimeOrigin::signed(2), None, 3));
+		assert_eq!(tally(3), Tally::from_parts(0, 0, 0));
+
+		assert_ok!(Voting::unlock(RuntimeOrigin::signed(1), class(3), 1));
+		assert_eq!(Balances::usable_balance(1), 10);
+
+		assert_ok!(Voting::unlock(RuntimeOrigin::signed(2), class(3), 2));
+		assert_eq!(Balances::usable_balance(2), 20);
+	});
+}
+
 #[test]
 fn voting_balance_gets_locked() {
 	new_test_ext().execute_with(|| {

frame/conviction-voting/src/types.rs

@@ -147,6 +147,15 @@ impl<
 				self.ayes = self.ayes.checked_add(&aye.votes)?;
 				self.nays = self.nays.checked_add(&nay.votes)?;
 			},
+			AccountVote::SplitAbstain { aye, nay, abstain } => {
+				let aye = Conviction::None.votes(aye);
+				let nay = Conviction::None.votes(nay);
+				let abstain = Conviction::None.votes(abstain);
+				self.support =
+					self.support.checked_add(&aye.capital)?.checked_add(&abstain.capital)?;
+				self.ayes = self.ayes.checked_add(&aye.votes)?;
+				self.nays = self.nays.checked_add(&nay.votes)?;
+			},
 		}
 		Some(())
 	}
@@ -171,6 +180,15 @@ impl<
 				self.ayes = self.ayes.checked_sub(&aye.votes)?;
 				self.nays = self.nays.checked_sub(&nay.votes)?;
 			},
+			AccountVote::SplitAbstain { aye, nay, abstain } => {
+				let aye = Conviction::None.votes(aye);
+				let nay = Conviction::None.votes(nay);
+				let abstain = Conviction::None.votes(abstain);
+				self.support =
+					self.support.checked_sub(&aye.capital)?.checked_sub(&abstain.capital)?;
+				self.ayes = self.ayes.checked_sub(&aye.votes)?;
+				self.nays = self.nays.checked_sub(&nay.votes)?;
+			},
 		}
 		Some(())
 	}

frame/conviction-voting/src/vote.rs

@@ -74,6 +74,10 @@ pub enum AccountVote<Balance> {
 	/// A split vote with balances given for both ways, and with no conviction, useful for
 	/// parachains when voting.
 	Split { aye: Balance, nay: Balance },
+	/// A split vote with balances given for both ways as well as abstentions, and with no
+	/// conviction, useful for parachains when voting, other off-chain aggregate accounts and
+	/// individuals who wish to abstain.
+	SplitAbstain { aye: Balance, nay: Balance, abstain: Balance },
 }
 
 impl<Balance: Saturating> AccountVote<Balance> {
@@ -94,6 +98,8 @@ impl<Balance: Saturating> AccountVote<Balance> {
 		match self {
 			AccountVote::Standard { balance, .. } => balance,
 			AccountVote::Split { aye, nay } => aye.saturating_add(nay),
+			AccountVote::SplitAbstain { aye, nay, abstain } =>
+				aye.saturating_add(nay).saturating_add(abstain),
 		}
 	}