Referendum threshold

substrate/frame/democracy/src/lib.rs

@@ -418,7 +418,7 @@
     use frame_system::{pallet_prelude::*, RawOrigin};
 
     #[pallet::pallet]
     #[pallet::generate_store(pub(super) trait Store)]
     #[pallet::without_storage_info]
     pub struct Pallet<T>(_);
 
@@ -780,6 +780,12 @@
             recipient: T::AccountId,
             deposit: BalanceOf<T>,
         },
+        /// Referendum threshold was updated.
+        ReferendumThresholdUpdated {
+            ref_index: ReferendumIndex,
+            old_threshold: VoteThreshold,
+            new_threshold: VoteThreshold,
+        },
     }
 
     #[pallet::error]
@@ -1610,6 +1616,37 @@
             }
             .into())
         }
+
+        /// Sets new threshold for the ongoing referendum.
+        #[pallet::weight(T::DbWeight::get().writes(1))]
+        pub fn set_referendum_threshold(
+            origin: OriginFor<T>,
+            ref_index: ReferendumIndex,
+            new_threshold: VoteThreshold,
+        ) -> DispatchResult {
+            ensure_root(origin)?;
+
+            ReferendumInfoOf::<T>::try_mutate(ref_index, |info_opt| {
+                let status = info_opt
+                    .as_mut()
+                    .and_then(|info| match info {
+                        ReferendumInfo::Ongoing(status) => Some(status),
+                        _ => None,
+                    })
+                    .ok_or(Error::<T>::ReferendumInvalid)?;
+
+                let old_threshold = status.threshold;
+                status.threshold = new_threshold;
+
+                Self::deposit_event(Event::<T>::ReferendumThresholdUpdated {
+                    ref_index,
+                    old_threshold,
+                    new_threshold,
+                });
+
+                Ok(())
+            })
+        }
     }
 }
 

substrate/frame/democracy/src/tests/voting.rs

@@ -17,6 +17,8 @@
 
 //! The tests for normal voting functionality.
 
+use frame_system::RawOrigin;
+
 use super::*;
 
 #[test]
@@ -155,6 +157,50 @@ fn controversial_voting_should_work() {
     });
 }
 
+#[test]
+fn set_threshold_should_work() {
+    new_test_ext().execute_with(|| {
+        let r = Democracy::inject_referendum(
+            2,
+            set_balance_proposal_hash_and_note(2),
+            VoteThreshold::SuperMajorityAgainst,
+            0,
+        );
+
+        assert_ok!(Democracy::vote(Origin::signed(1), r, aye(1)));
+        assert_ok!(Democracy::vote(Origin::signed(2), r, nay(2)));
+        assert_ok!(Democracy::vote(Origin::signed(3), r, nay(3)));
+        assert_ok!(Democracy::vote(Origin::signed(4), r, aye(4)));
+
+        assert_eq!(
+            tally(r),
+            Tally {
+                ayes: 5,
+                nays: 5,
+                turnout: 100
+            }
+        );
+        assert_ok!(Democracy::set_referendum_threshold(
+            RawOrigin::Root.into(),
+            r,
+            VoteThreshold::SuperMajorityApprove
+        ));
+
+        next_block();
+        next_block();
+
+        assert_eq!(Balances::free_balance(42), 0);
+        assert_noop!(
+            Democracy::set_referendum_threshold(
+                RawOrigin::Root.into(),
+                r,
+                VoteThreshold::SuperMajorityApprove
+            ),
+            Error::<Test>::ReferendumInvalid
+        );
+    });
+}
+
 #[test]
 fn controversial_low_turnout_voting_should_work() {
     new_test_ext().execute_with(|| {