Migrate generic-asset, identity and im-online to decl_error (#4473)

* Migrate generic-asset, identity and im-online to decl_error

* Update democracy tests

* Update nicks test

substrate/frame/generic-asset/src/lib.rs

@@ -151,7 +151,7 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use codec::{Decode, Encode, HasCompact, Input, Output, Error};
+use codec::{Decode, Encode, HasCompact, Input, Output, Error as CodecError};
 
 use sp_runtime::{RuntimeDebug, DispatchResult, DispatchError};
 use sp_runtime::traits::{
@@ -162,7 +162,7 @@ use sp_runtime::traits::{
 use sp_std::prelude::*;
 use sp_std::{cmp, result, fmt::Debug};
 use frame_support::{
-	decl_event, decl_module, decl_storage, ensure, dispatch,
+	decl_event, decl_module, decl_storage, ensure, dispatch, decl_error,
 	traits::{
 		Currency, ExistenceRequirement, Imbalance, LockIdentifier, LockableCurrency, ReservableCurrency,
 		SignedImbalance, UpdateBalanceOutcome, WithdrawReason, WithdrawReasons, TryDrop,
@@ -285,7 +285,7 @@ impl<AccountId: Encode> Encode for PermissionVersions<AccountId> {
 impl<AccountId: Encode> codec::EncodeLike for PermissionVersions<AccountId> {}
 
 impl<AccountId: Decode> Decode for PermissionVersions<AccountId> {
-	fn decode<I: Input>(input: &mut I) -> core::result::Result<Self, Error> {
+	fn decode<I: Input>(input: &mut I) -> core::result::Result<Self, CodecError> {
 		let version = PermissionVersionNumber::decode(input)?;
 		Ok(
 			match version {
@@ -320,8 +320,42 @@ impl<AccountId> Into<PermissionVersions<AccountId>> for PermissionLatest<Account
 	}
 }
 
+decl_error! {
+	/// Error for the identity module.
+	pub enum Error for Module<T: Trait> {
+		/// No new assets id available.
+		NoIdAvailable,
+		/// Cannot transfer zero amount.
+		ZeroAmount,
+		/// The origin does not have enough permission to update permissions.
+		NoUpdatePermission,
+		/// The origin does not have permission to mint an asset.
+		NoMintPermission,
+		/// The origin does not have permission to burn an asset.
+		NoBurnPermission,
+		/// Total issuance got overflowed after minting.
+		TotalMintingOverflow,
+		/// Free balance got overflowed after minting.
+		FreeMintingOverflow,
+		/// Total issuance got underflowed after burning.
+		TotalBurningUnderflow,
+		/// Free balance got underflowed after burning.
+		FreeBurningUnderflow,
+		/// Asset id is already taken.
+		IdAlreadyTaken,
+		/// Asset id not available.
+		IdUnavailable,
+		/// The balance is too low to send amount.
+		InsufficientBalance,
+		/// The account liquidity restrictions prevent withdrawal.
+		LiquidityRestrictions,
+	}
+}
+
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+		type Error = Error<T>;
+
 		fn deposit_event() = default;
 
 		/// Create a new kind of asset.
@@ -332,7 +366,7 @@ decl_module! {
 			let permissions: PermissionVersions<T::AccountId> = options.permissions.clone().into();
 
 			// The last available id serves as the overflow mark and won't be used.
-			let next_id = id.checked_add(&One::one()).ok_or_else(|| "No new assets id available.")?;
+			let next_id = id.checked_add(&One::one()).ok_or_else(|| Error::<T>::NoIdAvailable)?;
 
 			<NextAssetId<T>>::put(next_id);
 			<TotalIssuance<T>>::insert(id, &options.initial_issuance);
@@ -347,7 +381,7 @@ decl_module! {
 		/// Transfer some liquid free balance to another account.
 		pub fn transfer(origin, #[compact] asset_id: T::AssetId, to: T::AccountId, #[compact] amount: T::Balance) {
 			let origin = ensure_signed(origin)?;
-			ensure!(!amount.is_zero(), "cannot transfer zero amount");
+			ensure!(!amount.is_zero(), Error::<T>::ZeroAmount);
 			Self::make_transfer_with_event(&asset_id, &origin, &to, amount)?;
 		}
 
@@ -370,7 +404,7 @@ decl_module! {
 
 				Ok(())
 			} else {
-				Err("Origin does not have enough permission to update permissions.")?
+				Err(Error::<T>::NoUpdatePermission)?
 			}
 		}
 
@@ -384,9 +418,9 @@ decl_module! {
 				let original_free_balance = Self::free_balance(&asset_id, &to);
 				let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
 				let new_total_issuance = current_total_issuance.checked_add(&amount)
-					.ok_or_else(|| "total_issuance got overflow after minting.")?;
+					.ok_or(Error::<T>::TotalMintingOverflow)?;
 				let value = original_free_balance.checked_add(&amount)
-					.ok_or_else(|| "free balance got overflow after minting.")?;
+					.ok_or(Error::<T>::FreeMintingOverflow)?;
 
 				<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
 				Self::set_free_balance(&asset_id, &to, value);
@@ -395,7 +429,7 @@ decl_module! {
 
 				Ok(())
 			} else {
-				Err("The origin does not have permission to mint an asset.")?
+				Err(Error::<T>::NoMintPermission)?
 			}
 		}
 
@@ -412,9 +446,9 @@ decl_module! {
 
 				let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
 				let new_total_issuance = current_total_issuance.checked_sub(&amount)
-					.ok_or_else(|| "total_issuance got underflow after burning")?;
+					.ok_or(Error::<T>::TotalBurningUnderflow)?;
 				let value = original_free_balance.checked_sub(&amount)
-					.ok_or_else(|| "free_balance got underflow after burning")?;
+					.ok_or(Error::<T>::FreeBurningUnderflow)?;
 
 				<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
 
@@ -424,7 +458,7 @@ decl_module! {
 
 				Ok(())
 			} else {
-				Err("The origin does not have permission to burn an asset.")?
+				Err(Error::<T>::NoBurnPermission)?
 			}
 		}
 
@@ -545,14 +579,14 @@ impl<T: Trait> Module<T> {
 		options: AssetOptions<T::Balance, T::AccountId>,
 	) -> dispatch::DispatchResult {
 		let asset_id = if let Some(asset_id) = asset_id {
-			ensure!(!<TotalIssuance<T>>::exists(&asset_id), "Asset id already taken.");
-			ensure!(asset_id < Self::next_asset_id(), "Asset id not available.");
+			ensure!(!<TotalIssuance<T>>::exists(&asset_id), Error::<T>::IdAlreadyTaken);
+			ensure!(asset_id < Self::next_asset_id(), Error::<T>::IdUnavailable);
 			asset_id
 		} else {
 			let asset_id = Self::next_asset_id();
 			let next_id = asset_id
 				.checked_add(&One::one())
-				.ok_or_else(|| "No new user asset id available.")?;
+				.ok_or(Error::<T>::NoIdAvailable)?;
 			<NextAssetId<T>>::put(next_id);
 			asset_id
 		};
@@ -579,7 +613,7 @@ impl<T: Trait> Module<T> {
 	) -> dispatch::DispatchResult {
 		let new_balance = Self::free_balance(asset_id, from)
 			.checked_sub(&amount)
-			.ok_or_else(|| "balance too low to send amount")?;
+			.ok_or(Error::<T>::InsufficientBalance)?;
 		Self::ensure_can_withdraw(asset_id, from, amount, WithdrawReason::Transfer.into(), new_balance)?;
 
 		if from != to {
@@ -618,7 +652,7 @@ impl<T: Trait> Module<T> {
 		let original_reserve_balance = Self::reserved_balance(asset_id, who);
 		let original_free_balance = Self::free_balance(asset_id, who);
 		if original_free_balance < amount {
-			Err("not enough free funds")?
+			Err(Error::<T>::InsufficientBalance)?
 		}
 		let new_reserve_balance = original_reserve_balance + amount;
 		Self::set_reserved_balance(asset_id, who, new_reserve_balance);
@@ -767,7 +801,7 @@ impl<T: Trait> Module<T> {
 		{
 			Ok(())
 		} else {
-			Err("account liquidity restrictions prevent withdrawal")?
+			Err(Error::<T>::LiquidityRestrictions)?
 		}
 	}
 
@@ -1155,7 +1189,7 @@ where
 	) -> result::Result<Self::NegativeImbalance, DispatchError> {
 		let new_balance = Self::free_balance(who)
 			.checked_sub(&value)
-			.ok_or_else(|| "account has too few funds")?;
+			.ok_or(Error::<T>::InsufficientBalance)?;
 		Self::ensure_can_withdraw(who, value, reasons, new_balance)?;
 		<Module<T>>::set_free_balance(&U::asset_id(), who, new_balance);
 		Ok(NegativeImbalance::new(value))