Update conversion approach

frame/dvm/ethereum/src/account_basic.rs

@@ -1,3 +1,4 @@
+use frame_support::debug;
 use frame_support::traits::Currency;
 use pallet_evm::{Account as EVMAccount, AccountBasicMapping, AddressMapping};
 use sp_core::{H160, U256};
@@ -15,22 +16,22 @@ impl<T: crate::Trait + darwinia_balances::Trait<darwinia_balances::Instance0>> A
 		let helper = U256::from(10).overflowing_pow(U256::from(9)).0;
 
 		// Get balance from T::Currency
-		let balance = T::Currency::free_balance(&account_id);
-		let balance = U256::from(UniqueSaturatedInto::<u128>::unique_saturated_into(balance));
+		let balance: U256 = T::Currency::free_balance(&account_id)
+			.unique_saturated_into()
+			.into();
 
 		// Get remaining balance from dvm
-		let remaining_balance = crate::Module::<T>::remaining_balance(&account_id);
-		let remaining_balance = U256::from(UniqueSaturatedInto::<u128>::unique_saturated_into(
-			remaining_balance,
-		));
+		let remaining_balance: U256 = crate::Module::<T>::remaining_balance(&account_id)
+			.unique_saturated_into()
+			.into();
 
 		// Final balance = balance * 10^9 + remaining_balance
 		let final_balance = U256::from(balance * helper)
 			.overflowing_add(remaining_balance)
 			.0;
 
 		EVMAccount {
-			nonce: U256::from(UniqueSaturatedInto::<u128>::unique_saturated_into(nonce)),
+			nonce: nonce.unique_saturated_into().into(),
 			balance: final_balance,
 		}
 	}

frame/dvm/ethereum/src/lib.rs

@@ -33,7 +33,7 @@ use frame_system::ensure_none;
 use sha3::{Digest, Keccak256};
 use sp_runtime::{
 	generic::DigestItem,
-	traits::UniqueSaturatedInto,
+	traits::{Saturating, UniqueSaturatedInto},
 	transaction_validity::{
 		InvalidTransaction, TransactionSource, TransactionValidity, ValidTransaction,
 	},
@@ -45,7 +45,7 @@ pub use dvm_rpc_primitives::TransactionStatus;
 pub use ethereum::{Block, Log, Receipt, Transaction, TransactionAction};
 use frame_support::traits::Currency;
 use pallet_evm::{AccountBasicMapping, AddressMapping};
-use sp_runtime::traits::{CheckedAdd, CheckedSub};
+use sp_runtime::traits::CheckedSub;
 
 #[cfg(all(feature = "std", test))]
 mod tests;
@@ -323,9 +323,7 @@ impl<T: Trait> Module<T> {
 	/// Inc remaining balance
 	pub fn inc_remain_balance(account_id: &T::AccountId, value: T::Balance) {
 		let remain_balance = Self::remaining_balance(account_id);
-		let updated_balance = remain_balance
-			.checked_add(&value)
-			.expect("Inc remain balance, panic!");
+		let updated_balance = remain_balance.saturating_add(value);
 		<RemainingBalance<T>>::insert(account_id, updated_balance);
 	}