Add Deposit and Withdraw Events to Balances Pallet (#9425)

* add Deposit and Withdraw events to balances

+ add deposit_event() calls where appropriate to signal fund movement
+ adjust and extend tests

* line length

* move events to the end to avoid changing indices

* bump spec_version

* cargo fmt

* adjust block import bench to new event count

* fix node executor tests

* adjust import bench comment

* fix typo and formatting

* adjust event number

* fix copy pasta

* fix contracts pallets tests

* cargo fmt

* WIP fix events in tests

* fix offences tests

* fix tests

* cargo +nightly fmt

* fix contracts pallets tests

* cargo +nightly fmt

* fix offences tests

* formatting and compile fixes

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/balances/src/lib.rs

@@ -463,8 +463,6 @@ pub mod pallet {
 		Transfer(T::AccountId, T::AccountId, T::Balance),
 		/// A balance was set by root. \[who, free, reserved\]
 		BalanceSet(T::AccountId, T::Balance, T::Balance),
-		/// Some amount was deposited (e.g. for transaction fees). \[who, deposit\]
-		Deposit(T::AccountId, T::Balance),
 		/// Some balance was reserved (moved from free to reserved). \[who, value\]
 		Reserved(T::AccountId, T::Balance),
 		/// Some balance was unreserved (moved from reserved to free). \[who, value\]
@@ -473,6 +471,14 @@ pub mod pallet {
 		/// Final argument indicates the destination balance type.
 		/// \[from, to, balance, destination_status\]
 		ReserveRepatriated(T::AccountId, T::AccountId, T::Balance, Status),
+		/// Some amount was deposited into the account (e.g. for transaction fees). \[who,
+		/// deposit\]
+		Deposit(T::AccountId, T::Balance),
+		/// Some amount was withdrawn from the account (e.g. for transaction fees). \[who, value\]
+		Withdraw(T::AccountId, T::Balance),
+		/// Some amount was removed from the account (e.g. for misbehavior). \[who,
+		/// amount_slashed\]
+		Slashed(T::AccountId, T::Balance),
 	}
 
 	/// Old name generated by `decl_event`.
@@ -1103,6 +1109,7 @@ impl<T: Config<I>, I: 'static> fungible::Mutate<T::AccountId> for Pallet<T, I> {
 			Ok(())
 		})?;
 		TotalIssuance::<T, I>::mutate(|t| *t += amount);
+		Self::deposit_event(Event::Deposit(who.clone(), amount));
 		Ok(())
 	}
 
@@ -1123,6 +1130,7 @@ impl<T: Config<I>, I: 'static> fungible::Mutate<T::AccountId> for Pallet<T, I> {
 			},
 		)?;
 		TotalIssuance::<T, I>::mutate(|t| *t -= actual);
+		Self::deposit_event(Event::Withdraw(who.clone(), amount));
 		Ok(actual)
 	}
 }
@@ -1141,7 +1149,10 @@ impl<T: Config<I>, I: 'static> fungible::Transfer<T::AccountId> for Pallet<T, I>
 
 impl<T: Config<I>, I: 'static> fungible::Unbalanced<T::AccountId> for Pallet<T, I> {
 	fn set_balance(who: &T::AccountId, amount: Self::Balance) -> DispatchResult {
-		Self::mutate_account(who, |account| account.free = amount)?;
+		Self::mutate_account(who, |account| {
+			account.free = amount;
+			Self::deposit_event(Event::BalanceSet(who.clone(), account.free, account.reserved));
+		})?;
 		Ok(())
 	}
 
@@ -1583,7 +1594,13 @@ where
 					}
 				},
 			) {
-				Ok(r) => return r,
+				Ok((imbalance, not_slashed)) => {
+					Self::deposit_event(Event::Slashed(
+						who.clone(),
+						value.saturating_sub(not_slashed),
+					));
+					return (imbalance, not_slashed)
+				},
 				Err(_) => (),
 			}
 		}
@@ -1608,6 +1625,7 @@ where
 			|account, is_new| -> Result<Self::PositiveImbalance, DispatchError> {
 				ensure!(!is_new, Error::<T, I>::DeadAccount);
 				account.free = account.free.checked_add(&value).ok_or(ArithmeticError::Overflow)?;
+				Self::deposit_event(Event::Deposit(who.clone(), value));
 				Ok(PositiveImbalance::new(value))
 			},
 		)
@@ -1640,6 +1658,7 @@ where
 					None => return Ok(Self::PositiveImbalance::zero()),
 				};
 
+				Self::deposit_event(Event::Deposit(who.clone(), value));
 				Ok(PositiveImbalance::new(value))
 			},
 		)
@@ -1677,6 +1696,7 @@ where
 
 				account.free = new_free_account;
 
+				Self::deposit_event(Event::Withdraw(who.clone(), value));
 				Ok(NegativeImbalance::new(value))
 			},
 		)
@@ -1709,6 +1729,7 @@ where
 					SignedImbalance::Negative(NegativeImbalance::new(account.free - value))
 				};
 				account.free = value;
+				Self::deposit_event(Event::BalanceSet(who.clone(), account.free, account.reserved));
 				Ok(imbalance)
 			},
 		)
@@ -1824,7 +1845,13 @@ where
 				// underflow should never happen, but it if does, there's nothing to be done here.
 				(NegativeImbalance::new(actual), value - actual)
 			}) {
-				Ok(r) => return r,
+				Ok((imbalance, not_slashed)) => {
+					Self::deposit_event(Event::Slashed(
+						who.clone(),
+						value.saturating_sub(not_slashed),
+					));
+					return (imbalance, not_slashed)
+				},
 				Err(_) => (),
 			}
 		}
@@ -1965,6 +1992,7 @@ where
 					// `actual <= to_change` and `to_change <= amount`; qed;
 					reserves[index].amount -= actual;
 
+					Self::deposit_event(Event::Slashed(who.clone(), actual));
 					(imb, value - actual)
 				},
 				Err(_) => (NegativeImbalance::zero(), value),