Fix Collective <-> Elections initialization. (#5454)

* A patch

* Fix

* Better approach.

* Fix grumbles

substrate/frame/elections-phragmen/src/lib.rs

@@ -91,7 +91,7 @@ use frame_support::{
 	weights::{SimpleDispatchInfo, Weight, WeighData}, storage::{StorageMap, IterableStorageMap},
 	traits::{
 		Currency, Get, LockableCurrency, LockIdentifier, ReservableCurrency, WithdrawReasons,
-		ChangeMembers, OnUnbalanced, WithdrawReason, Contains, BalanceStatus
+		ChangeMembers, OnUnbalanced, WithdrawReason, Contains, BalanceStatus, InitializeMembers,
 	}
 };
 use sp_phragmen::{build_support_map, ExtendedBalance};
@@ -118,6 +118,9 @@ pub trait Trait: frame_system::Trait {
 	/// What to do when the members change.
 	type ChangeMembers: ChangeMembers<Self::AccountId>;
 
+	/// What to do with genesis members
+	type InitializeMembers: InitializeMembers<Self::AccountId>;
+
 	/// Convert a balance into a number used for election calculation.
 	/// This must fit into a `u64` but is allowed to be sensibly lossy.
 	type CurrencyToVote: Convert<BalanceOf<Self>, u64> + Convert<u128, BalanceOf<Self>>;
@@ -160,11 +163,44 @@ decl_storage! {
 		pub ElectionRounds get(fn election_rounds): u32 = Zero::zero();
 
 		/// Votes and locked stake of a particular voter.
-		pub Voting: map hasher(twox_64_concat) T::AccountId => (BalanceOf<T>, Vec<T::AccountId>);
+		pub Voting get(fn voting): map hasher(twox_64_concat) T::AccountId => (BalanceOf<T>, Vec<T::AccountId>);
 
 		/// The present candidate list. Sorted based on account-id. A current member or runner-up
 		/// can never enter this vector and is always implicitly assumed to be a candidate.
 		pub Candidates get(fn candidates): Vec<T::AccountId>;
+	} add_extra_genesis {
+		config(members): Vec<(T::AccountId, BalanceOf<T>)>;
+		build(|config: &GenesisConfig<T>| {
+			let members = config.members.iter().map(|(ref member, ref stake)| {
+				// make sure they have enough stake
+				assert!(
+					T::Currency::free_balance(member) >= *stake,
+					"Genesis member does not have enough stake",
+				);
+
+				// reserve candidacy bond and set as members.
+				T::Currency::reserve(&member, T::CandidacyBond::get())
+					.expect("Genesis member does not have enough balance to be a candidate");
+
+				// Note: all members will only vote for themselves, hence they must be given exactly
+				// their own stake as total backing. Any sane election should behave as such.
+				// Nonetheless, stakes will be updated for term 1 onwards according to the election.
+				<Members<T>>::append(&[(member.clone(), *stake)])
+					.expect("Failed to append genesis members.");
+
+				// set self-votes to make persistent.
+				<Module<T>>::vote(
+					T::Origin::from(Some(member.clone()).into()),
+					vec![member.clone()],
+					*stake,
+				).expect("Genesis member could not vote.");
+
+				member.clone()
+			}).collect::<Vec<T::AccountId>>();
+
+			// report genesis members to upstream, if any.
+			T::InitializeMembers::initialize_members(&members);
+		})
 	}
 }
 
@@ -844,7 +880,7 @@ mod tests {
 		Perbill, testing::Header, BuildStorage,
 		traits::{BlakeTwo256, IdentityLookup, Block as BlockT},
 	};
-	use crate as elections;
+	use crate as elections_phragmen;
 	use frame_system as system;
 
 	parameter_types! {
@@ -980,6 +1016,7 @@ mod tests {
 		type Currency = Balances;
 		type CurrencyToVote = CurrencyToVoteHandler;
 		type ChangeMembers = TestChangeMembers;
+		type InitializeMembers = ();
 		type CandidacyBond = CandidacyBond;
 		type VotingBond = VotingBond;
 		type TermDuration = TermDuration;
@@ -1001,11 +1038,12 @@ mod tests {
 		{
 			System: system::{Module, Call, Event<T>},
 			Balances: pallet_balances::{Module, Call, Event<T>, Config<T>},
-			Elections: elections::{Module, Call, Event<T>},
+			Elections: elections_phragmen::{Module, Call, Event<T>, Config<T>},
 		}
 	);
 
 	pub struct ExtBuilder {
+		genesis_members: Vec<(u64, u64)>,
 		balance_factor: u64,
 		voter_bond: u64,
 		term_duration: u64,
@@ -1015,6 +1053,7 @@ mod tests {
 	impl Default for ExtBuilder {
 		fn default() -> Self {
 			Self {
+				genesis_members: vec![],
 				balance_factor: 1,
 				voter_bond: 2,
 				desired_runners_up: 0,
@@ -1036,10 +1075,15 @@ mod tests {
 			self.term_duration = duration;
 			self
 		}
+		pub fn genesis_members(mut self, members: Vec<(u64, u64)>) -> Self {
+			self.genesis_members = members;
+			self
+		}
 		pub fn build(self) -> sp_io::TestExternalities {
 			VOTING_BOND.with(|v| *v.borrow_mut() = self.voter_bond);
 			TERM_DURATION.with(|v| *v.borrow_mut() = self.term_duration);
 			DESIRED_RUNNERS_UP.with(|v| *v.borrow_mut() = self.desired_runners_up);
+			MEMBERS.with(|m| *m.borrow_mut() = self.genesis_members.iter().map(|(m, _)| m.clone()).collect::<Vec<_>>());
 			let mut ext: sp_io::TestExternalities = GenesisConfig {
 				pallet_balances: Some(pallet_balances::GenesisConfig::<Test>{
 					balances: vec![
@@ -1051,6 +1095,9 @@ mod tests {
 						(6, 60 * self.balance_factor)
 					],
 				}),
+				elections_phragmen: Some(elections_phragmen::GenesisConfig::<Test> {
+					members: self.genesis_members
+				}),
 			}.build_storage().unwrap().into();
 			ext.execute_with(|| System::set_block_number(1));
 			ext
@@ -1090,6 +1137,37 @@ mod tests {
 		});
 	}
 
+	#[test]
+	fn genesis_members_should_work() {
+		ExtBuilder::default().genesis_members(vec![(1, 10), (2, 20)]).build().execute_with(|| {
+			System::set_block_number(1);
+			assert_eq!(Elections::members(), vec![(1, 10), (2, 20)]);
+
+			assert_eq!(Elections::voting(1), (10, vec![1]));
+			assert_eq!(Elections::voting(2), (20, vec![2]));
+
+			// they will persist since they have self vote.
+			System::set_block_number(5);
+			assert_ok!(Elections::end_block(System::block_number()));
+
+			assert_eq!(Elections::members_ids(), vec![1, 2]);
+		})
+	}
+
+	#[test]
+	#[should_panic = "Genesis member does not have enough stake"]
+	fn genesis_members_cannot_over_stake_0() {
+		// 10 cannot lock 20 as their stake and extra genesis will panic.
+		ExtBuilder::default().genesis_members(vec![(1, 20), (2, 20)]).build();
+	}
+
+	#[test]
+	#[should_panic]
+	fn genesis_members_cannot_over_stake_1() {
+		// 10 cannot reserve 20 as voting bond and extra genesis will panic.
+		ExtBuilder::default().voter_bond(20).genesis_members(vec![(1, 10), (2, 20)]).build();
+	}
+
 	#[test]
 	fn term_duration_zero_is_passive() {
 		ExtBuilder::default()
@@ -1538,7 +1616,7 @@ mod tests {
 
 			assert_ok!(Elections::report_defunct_voter(Origin::signed(5), 3));
 			assert!(System::events().iter().any(|event| {
-				event.event == Event::elections(RawEvent::VoterReported(3, 5, true))
+				event.event == Event::elections_phragmen(RawEvent::VoterReported(3, 5, true))
 			}));
 
 			assert_eq!(balances(&3), (28, 0));
@@ -1566,7 +1644,7 @@ mod tests {
 
 			assert_ok!(Elections::report_defunct_voter(Origin::signed(5), 4));
 			assert!(System::events().iter().any(|event| {
-				event.event == Event::elections(RawEvent::VoterReported(4, 5, false))
+				event.event == Event::elections_phragmen(RawEvent::VoterReported(4, 5, false))
 			}));
 
 			assert_eq!(balances(&4), (35, 5));
@@ -1976,7 +2054,7 @@ mod tests {
 			assert_eq!(balances(&5), (45, 2));
 
 			assert!(System::events().iter().any(|event| {
-				event.event == Event::elections(RawEvent::NewTerm(vec![(4, 40), (5, 50)]))
+				event.event == Event::elections_phragmen(RawEvent::NewTerm(vec![(4, 40), (5, 50)]))
 			}));
 		})
 	}