feat: add event SkepticsChosen event in society (paritytech#13291)

* feat: add event SkepticsChosen event in society

* feat: add test for SkepticsChosen event

frame/society/src/lib.rs

@@ -513,6 +513,8 @@ pub mod pallet {
 		Unfounded { founder: T::AccountId },
 		/// Some funds were deposited into the society account.
 		Deposit { value: BalanceOf<T, I> },
+		/// A group of members has been choosen as Skeptics
+		SkepticsChosen { skeptics: Vec<T::AccountId> },
 	}
 
 	/// The first member.
@@ -1610,12 +1612,14 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 
 		// Select sqrt(n) random members from the society and make them skeptics.
 		let pick_member =
-			|_| pick_item(&mut rng, &members[..]).expect("exited if members empty; qed");
-		for skeptic in (0..members.len().integer_sqrt()).map(pick_member) {
+			|_| pick_item(&mut rng, &members[..]).expect("exited if members empty; qed").clone();
+		let skeptics = (0..members.len().integer_sqrt()).map(pick_member).collect::<Vec<_>>();
+		skeptics.iter().for_each(|skeptic| {
 			for Bid { who: c, .. } in candidates.iter() {
 				<Votes<T, I>>::insert(c, skeptic, Vote::Skeptic);
 			}
-		}
+		});
+		Self::deposit_event(Event::<T, I>::SkepticsChosen { skeptics });
 	}
 
 	/// Attempt to slash the payout of some member. Return the total amount that was deducted.

frame/society/src/tests.rs

@@ -211,13 +211,20 @@ fn payout_works() {
 #[test]
 fn basic_new_member_skeptic_works() {
 	EnvBuilder::new().execute(|| {
+		// NOTE: events are not deposited in the genesis event
+		System::set_block_number(1);
+
 		assert_eq!(Strikes::<Test>::get(10), 0);
 		assert_ok!(Society::bid(RuntimeOrigin::signed(20), 0));
 		run_to_block(4);
 		assert_eq!(Society::candidates(), vec![create_bid(0, 20, BidKind::Deposit(25))]);
 		run_to_block(8);
 		assert_eq!(Society::members(), vec![10]);
 		assert_eq!(Strikes::<Test>::get(10), 1);
+
+		System::assert_last_event(mock::RuntimeEvent::Society(crate::Event::SkepticsChosen {
+			skeptics: vec![10],
+		}));
 	});
 }