Fix: stash account reaped when ledger.active == ED (#8170)

* do not reap account when active == ed

* add tests + refactor

substrate/frame/staking/src/lib.rs

@@ -1638,7 +1638,7 @@ decl_module! {
 				ledger = ledger.consolidate_unlocked(current_era)
 			}
 
-			let post_info_weight = if ledger.unlocking.is_empty() && ledger.active <= T::Currency::minimum_balance() {
+			let post_info_weight = if ledger.unlocking.is_empty() && ledger.active < T::Currency::minimum_balance() {
 				// This account must have called `unbond()` with some value that caused the active
 				// portion to fall below existential deposit + will have no more unlocking chunks
 				// left. We can now safely remove all staking-related information.
@@ -3080,7 +3080,7 @@ impl<T: Config> Module<T> {
 	/// Assumes storage is upgraded before calling.
 	///
 	/// This is called:
-	/// - after a `withdraw_unbond()` call that frees all of a stash's bonded balance.
+	/// - after a `withdraw_unbonded()` call that frees all of a stash's bonded balance.
 	/// - through `reap_stash()` if the balance has fallen to zero (through slashing).
 	fn kill_stash(stash: &T::AccountId, num_slashing_spans: u32) -> DispatchResult {
 		let controller = <Bonded<T>>::get(stash).ok_or(Error::<T>::NotStash)?;

substrate/frame/staking/src/tests.rs

@@ -4978,3 +4978,40 @@ fn cannot_bond_extra_to_lower_than_ed() {
 			);
 		})
 }
+
+#[test]
+fn do_not_die_when_active_is_ed() {
+	let ed = 10;
+	ExtBuilder::default()
+		.existential_deposit(ed)
+		.build_and_execute(|| {
+			// initial stuff.
+			assert_eq!(
+				Staking::ledger(&20).unwrap(),
+				StakingLedger {
+					stash: 21,
+					total: 1000,
+					active: 1000,
+					unlocking: vec![],
+					claimed_rewards: vec![]
+				}
+			);
+
+			// unbond all of it except ed.
+			assert_ok!(Staking::unbond(Origin::signed(20), 1000 - ed));
+			start_active_era(3);
+			assert_ok!(Staking::withdraw_unbonded(Origin::signed(20), 100));
+
+			// initial stuff.
+			assert_eq!(
+				Staking::ledger(&20).unwrap(),
+				StakingLedger {
+					stash: 21,
+					total: ed,
+					active: ed,
+					unlocking: vec![],
+					claimed_rewards: vec![]
+				}
+			);
+		})
+}