Use reducible_balance instead free_balance (#420)

* Use `tokens::fungible::Inspect::reducible_balance`

* Integration test

* cargo fmt

* integration tests

* recipient's balance is also subject to ed

Co-authored-by: Joshy Orndorff <admin@joshyorndorff.com>
Co-authored-by: Joshy Orndorff <JoshOrndorff@users.noreply.github.com>

frame/evm/src/lib.rs

@@ -74,7 +74,8 @@ use codec::{Decode, Encode};
 use evm::Config as EvmConfig;
 use frame_support::dispatch::DispatchResultWithPostInfo;
 use frame_support::traits::{
-	Currency, ExistenceRequirement, FindAuthor, Get, Imbalance, OnUnbalanced, WithdrawReasons,
+	tokens::fungible::Inspect, Currency, ExistenceRequirement, FindAuthor, Get, Imbalance,
+	OnUnbalanced, WithdrawReasons,
 };
 use frame_support::weights::{Pays, PostDispatchInfo, Weight};
 use frame_system::RawOrigin;
@@ -118,7 +119,7 @@ pub mod pallet {
 		/// Mapping from address to account id.
 		type AddressMapping: AddressMapping<Self::AccountId>;
 		/// Currency type for withdraw and balance storage.
-		type Currency: Currency<Self::AccountId>;
+		type Currency: Currency<Self::AccountId> + Inspect<Self::AccountId>;
 
 		/// The overarching event type.
 		type Event: From<Event<Self>> + IsType<<Self as frame_system::Config>::Event>;
@@ -621,7 +622,8 @@ impl<T: Config> Pallet<T> {
 		let account_id = T::AddressMapping::into_account_id(*address);
 
 		let nonce = frame_system::Pallet::<T>::account_nonce(&account_id);
-		let balance = T::Currency::free_balance(&account_id);
+		// keepalive `true` takes into account ExistentialDeposit as part of what's considered liquid balance.
+		let balance = T::Currency::reducible_balance(&account_id, true);
 
 		Account {
 			nonce: U256::from(UniqueSaturatedInto::<u128>::unique_saturated_into(nonce)),

frame/evm/src/tests.rs

@@ -21,7 +21,7 @@ use super::*;
 use crate::mock::*;
 
 use frame_support::assert_ok;
-use frame_support::traits::GenesisBuild;
+use frame_support::traits::{GenesisBuild, LockIdentifier, LockableCurrency, WithdrawReasons};
 use std::{collections::BTreeMap, str::FromStr};
 
 type Balances = pallet_balances::Pallet<Test>;
@@ -121,3 +121,24 @@ fn find_author() {
 		);
 	});
 }
+
+#[test]
+fn reducible_balance() {
+	new_test_ext().execute_with(|| {
+		let evm_addr = H160::from_str("1000000000000000000000000000000000000001").unwrap();
+		let account_id = <Test as Config>::AddressMapping::into_account_id(evm_addr);
+		let existential = ExistentialDeposit::get();
+
+		// Genesis Balance.
+		let genesis_balance = EVM::account_basic(&evm_addr).balance;
+
+		// Lock identifier.
+		let lock_id: LockIdentifier = *b"te/stlok";
+		// Reserve some funds.
+		let to_lock = 1000;
+		Balances::set_lock(lock_id, &account_id, to_lock, WithdrawReasons::RESERVE);
+		// Reducible is, as currently configured in `account_basic`, (balance - lock + existential).
+		let reducible_balance = EVM::account_basic(&evm_addr).balance;
+		assert_eq!(reducible_balance, (genesis_balance - to_lock + existential));
+	});
+}

ts-tests/tests/test-balance.ts

@@ -5,7 +5,7 @@ import { createAndFinalizeBlock, describeWithFrontier, customRequest } from "./u
 
 describeWithFrontier("Frontier RPC (Balance)", (context) => {
 	const GENESIS_ACCOUNT = "0x6be02d1d3665660d22ff9624b7be0551ee1ac91b";
-	const GENESIS_ACCOUNT_BALANCE = "340282366920938463463374607431768211455";
+	const GENESIS_ACCOUNT_BALANCE = "340282366920938463463374607431768210955";
 	const GENESIS_ACCOUNT_PRIVATE_KEY = "0x99B3C12287537E38C90A9219D4CB074A89A16E9CDB20BF85728EBD97C343E342";
 	const TEST_ACCOUNT = "0x1111111111111111111111111111111111111111";
 
@@ -25,7 +25,7 @@ describeWithFrontier("Frontier RPC (Balance)", (context) => {
 		}, GENESIS_ACCOUNT_PRIVATE_KEY);
 		await customRequest(context.web3, "eth_sendRawTransaction", [tx.rawTransaction]);
 		await createAndFinalizeBlock(context.web3);
-		expect(await context.web3.eth.getBalance(GENESIS_ACCOUNT)).to.equal("340282366920938463463374607431768189943");
-		expect(await context.web3.eth.getBalance(TEST_ACCOUNT)).to.equal("512");
+		expect(await context.web3.eth.getBalance(GENESIS_ACCOUNT)).to.equal("340282366920938463463374607431768189443");
+		expect(await context.web3.eth.getBalance(TEST_ACCOUNT)).to.equal("12");
 	});
 });