Kill stash after unbonding all values

- check the ledge after unbond and kill stash after unbond all values

srml/staking/src/lib.rs

@@ -799,6 +799,11 @@ decl_module! {
 		///
 		/// The dispatch origin for this call must be _Signed_ by the controller, not the stash.
 		///
+		/// After all pledged Ring and Kton are unbonded, the bonded accounts, namely stash and
+		/// controller, will also be unbended.  Once user want to bond again, the `bond` method
+		/// should be called. If there are still pledged Ring or Kton and user want to bound more
+		/// values, the `bond_extra` method should be called.
+		///
 		/// # <weight>
 		/// - Independent of the arguments. Limited but potentially exploitable complexity.
 		/// - Contains a limited number of reads.
@@ -877,6 +882,22 @@ decl_module! {
 					}
 				},
 			}
+
+			let updated_ledger = Self::clear_mature_deposits(
+				Self::ledger(&controller).ok_or(err::CONTROLLER_INVALID)?);
+
+			let stash = ledger.stash.clone();
+			let StakingLedger {
+				active_ring,
+				active_deposit_ring,
+				active_kton,
+				..
+			} = updated_ledger;
+
+			// all bonded rings and ktons is withdrawing, then remove Ledger to save storage
+			if active_ring.is_zero() && active_deposit_ring.is_zero() && active_kton.is_zero() {
+				Self::kill_stash(&stash);
+			}
 		}
 
 		// TODO: doc

srml/staking/src/tests.rs

@@ -1993,37 +1993,17 @@ fn bond_with_no_staked_value() {
 				RewardDestination::Controller,
 				0,
 			));
-			//			assert_eq!(Ring::locks(&1)[0].amount, 5);
-
-			assert_ok!(Staking::unbond(Origin::signed(2), StakingBalances::RingBalance(5)));
-			assert_eq!(
-				Staking::ledger(2),
-				Some(StakingLedger {
-					stash: 1,
-					active_ring: 0,
-					active_deposit_ring: 0,
-					active_kton: 0,
-					deposit_items: vec![],
-					ring_staking_lock: StakingLock {
-						staking_amount: 0,
-						unbondings: vec![NormalLock { amount: 5, until: 60 }],
-					},
-					kton_staking_lock: Default::default(),
-				}),
-			);
-
-			Timestamp::set_timestamp(BondingDuration::get() - 1);
-
 			// Not yet removed.
 			assert!(Staking::ledger(2).is_some());
-			//			assert_eq!(Ring::locks(&1)[0].amount, 5);
+			match Ring::locks(&1)[0].withdraw_lock.clone() {
+				WithdrawLock::Normal(_) => panic!("lock type error"),
+				WithdrawLock::WithStaking(lock) => assert_eq!(lock.staking_amount, 5),
+			}
 
-			Timestamp::set_timestamp(BondingDuration::get());
+			assert_ok!(Staking::unbond(Origin::signed(2), StakingBalances::RingBalance(5)));
 
-			// FIXME
-			// Poof. Account 1 is removed from the staking system.
-			//			assert!(Staking::ledger(2).is_none());
-			//			assert_eq!(Ring::locks(&1).len(), 0);
+			// unbond all, auto remove the ledger
+			assert_eq!(Staking::ledger(2), None);
 		});
 }