pallet-evm: return Ok(()) when EVM execution fails (#6493)

* pallet-evm: return Ok(()) when EVM execution fails

* Bump spec version

* Init test module

* Add fail_call_return_ok test

* Fix tests and use full match pattern

Co-authored-by: Gav Wood <gavin@parity.io>

substrate/frame/evm/src/tests.rs

@@ -0,0 +1,169 @@
+#![cfg(test)]
+
+use super::*;
+
+use std::{str::FromStr, collections::BTreeMap};
+use frame_support::{
+	assert_ok, impl_outer_origin, parameter_types, impl_outer_dispatch,
+};
+use sp_core::H256;
+// The testing primitives are very useful for avoiding having to work with signatures
+// or public keys. `u64` is used as the `AccountId` and no `Signature`s are required.
+use sp_runtime::{
+	Perbill,
+	testing::Header,
+	traits::{BlakeTwo256, IdentityLookup},
+};
+
+impl_outer_origin! {
+	pub enum Origin for Test  where system = frame_system {}
+}
+
+impl_outer_dispatch! {
+	pub enum OuterCall for Test where origin: Origin {
+		self::EVM,
+	}
+}
+
+// For testing the pallet, we construct most of a mock runtime. This means
+// first constructing a configuration type (`Test`) which `impl`s each of the
+// configuration traits of pallets we want to use.
+#[derive(Clone, Eq, PartialEq)]
+pub struct Test;
+parameter_types! {
+	pub const BlockHashCount: u64 = 250;
+	pub const MaximumBlockWeight: Weight = 1024;
+	pub const MaximumBlockLength: u32 = 2 * 1024;
+	pub const AvailableBlockRatio: Perbill = Perbill::one();
+}
+impl frame_system::Trait for Test {
+	type BaseCallFilter = ();
+	type Origin = Origin;
+	type Index = u64;
+	type BlockNumber = u64;
+	type Hash = H256;
+	type Call = OuterCall;
+	type Hashing = BlakeTwo256;
+	type AccountId = H256;
+	type Lookup = IdentityLookup<Self::AccountId>;
+	type Header = Header;
+	type Event = ();
+	type BlockHashCount = BlockHashCount;
+	type MaximumBlockWeight = MaximumBlockWeight;
+	type DbWeight = ();
+	type BlockExecutionWeight = ();
+	type ExtrinsicBaseWeight = ();
+	type MaximumExtrinsicWeight = MaximumBlockWeight;
+	type MaximumBlockLength = MaximumBlockLength;
+	type AvailableBlockRatio = AvailableBlockRatio;
+	type Version = ();
+	type ModuleToIndex = ();
+	type AccountData = pallet_balances::AccountData<u64>;
+	type OnNewAccount = ();
+	type OnKilledAccount = ();
+}
+
+parameter_types! {
+	pub const ExistentialDeposit: u64 = 1;
+}
+impl pallet_balances::Trait for Test {
+	type Balance = u64;
+	type DustRemoval = ();
+	type Event = ();
+	type ExistentialDeposit = ExistentialDeposit;
+	type AccountStore = System;
+}
+
+parameter_types! {
+	pub const MinimumPeriod: u64 = 1000;
+}
+impl pallet_timestamp::Trait for Test {
+	type Moment = u64;
+	type OnTimestampSet = ();
+	type MinimumPeriod = MinimumPeriod;
+}
+
+/// Fixed gas price of `0`.
+pub struct FixedGasPrice;
+impl FeeCalculator for FixedGasPrice {
+	fn min_gas_price() -> U256 {
+		// Gas price is always one token per gas.
+		0.into()
+	}
+}
+parameter_types! {
+	pub const EVMModuleId: ModuleId = ModuleId(*b"py/evmpa");
+}
+impl Trait for Test {
+	type ChainId = SystemChainId;
+	type ModuleId = EVMModuleId;
+	type FeeCalculator = FixedGasPrice;
+	type ConvertAccountId = HashTruncateConvertAccountId<BlakeTwo256>;
+	type Currency = Balances;
+	type Event = Event<Test>;
+	type Precompiles = ();
+}
+
+type System = frame_system::Module<Test>;
+type Balances = pallet_balances::Module<Test>;
+type EVM = Module<Test>;
+
+// This function basically just builds a genesis storage key/value store according to
+// our desired mockup.
+pub fn new_test_ext() -> sp_io::TestExternalities {
+	let mut t = frame_system::GenesisConfig::default().build_storage::<Test>().unwrap();
+
+	let mut accounts = BTreeMap::new();
+	accounts.insert(
+		H160::from_str("1000000000000000000000000000000000000001").unwrap(),
+		GenesisAccount {
+			nonce: U256::from(1),
+			balance: U256::from(1000000),
+			storage: Default::default(),
+			code: vec![
+				0x00, // STOP
+			],
+		}
+	);
+	accounts.insert(
+		H160::from_str("1000000000000000000000000000000000000002").unwrap(),
+		GenesisAccount {
+			nonce: U256::from(1),
+			balance: U256::from(1000000),
+			storage: Default::default(),
+			code: vec![
+				0xff, // INVALID
+			],
+		}
+	);
+
+	// We use default for brevity, but you can configure as desired if needed.
+	pallet_balances::GenesisConfig::<Test>::default().assimilate_storage(&mut t).unwrap();
+	GenesisConfig { accounts }.assimilate_storage(&mut t).unwrap();
+	t.into()
+}
+
+#[test]
+fn fail_call_return_ok() {
+	new_test_ext().execute_with(|| {
+		assert_ok!(EVM::call(
+			Origin::signed(H256::default()),
+			H160::from_str("1000000000000000000000000000000000000001").unwrap(),
+			Vec::new(),
+			U256::default(),
+			1000000,
+			U256::default(),
+			None,
+		));
+
+		assert_ok!(EVM::call(
+			Origin::signed(H256::default()),
+			H160::from_str("1000000000000000000000000000000000000002").unwrap(),
+			Vec::new(),
+			U256::default(),
+			1000000,
+			U256::default(),
+			None,
+		));
+	});
+}