Add support for estimate gas historically (polkadot-evm#1031)

* Add support for estimate gas historically

* prettier

client/rpc/src/eth/execute.rs

@@ -351,15 +351,36 @@ where
 		}
 	}
 
-	pub async fn estimate_gas(&self, request: CallRequest, _: Option<BlockNumber>) -> Result<U256> {
+	pub async fn estimate_gas(
+		&self,
+		request: CallRequest,
+		number: Option<BlockNumber>,
+	) -> Result<U256> {
 		let client = Arc::clone(&self.client);
 		let block_data_cache = Arc::clone(&self.block_data_cache);
 
 		// Define the lower bound of estimate
 		const MIN_GAS_PER_TX: U256 = U256([21_000, 0, 0, 0]);
 
-		// Get best hash (TODO missing support for estimating gas historically)
-		let substrate_hash = client.info().best_hash;
+		// Get substrate hash and runtime api
+		let (substrate_hash, api) = match frontier_backend_client::native_block_id::<B, C>(
+			self.client.as_ref(),
+			self.backend.as_ref(),
+			number,
+		)? {
+			Some(id) => {
+				let hash = client
+					.expect_block_hash_from_id(&id)
+					.map_err(|_| crate::err(JSON_RPC_ERROR_DEFAULT, "header not found", None))?;
+				(hash, client.runtime_api())
+			}
+			None => {
+				// Not mapped in the db, assume pending.
+				let hash = client.info().best_hash;
+				let api = pending_runtime_api(client.as_ref(), self.graph.as_ref())?;
+				(hash, api)
+			}
+		};
 
 		// Adapt request for gas estimation.
 		let request = EC::EstimateGasAdapter::adapt_request(request);
@@ -371,8 +392,7 @@ where
 		};
 		if is_simple_transfer {
 			if let Some(to) = request.to {
-				let to_code = client
-					.runtime_api()
+				let to_code = api
 					.account_code_at(substrate_hash, to)
 					.map_err(|err| internal_err(format!("runtime error: {:?}", err)))?;
 				if to_code.is_empty() {
@@ -405,8 +425,6 @@ where
 
 		let max_gas_limit = block_gas_limit * self.execute_gas_limit_multiplier;
 
-		let api = client.runtime_api();
-
 		// Determine the highest possible gas limits
 		let mut highest = match request.gas {
 			Some(amount) => {

ts-tests/tests/test-execute.ts

@@ -6,14 +6,109 @@ import { describeWithFrontier, customRequest, createAndFinalizeBlock } from "./u
 import { AbiItem } from "web3-utils";
 
 import Test from "../build/contracts/Test.json";
+import Storage from "../build/contracts/Storage.json";
 import ForceGasLimit from "../build/contracts/ForceGasLimit.json";
 
 const TEST_CONTRACT_BYTECODE = Test.bytecode;
 const TEST_CONTRACT_DEPLOYED_BYTECODE = Test.deployedBytecode;
 
 const FORCE_GAS_CONTRACT_BYTECODE = ForceGasLimit.bytecode;
 const FORCE_GAS_CONTRACT_ABI = ForceGasLimit.abi as AbiItem[];
-const FORCE_GAS_CONTRACT_DEPLOYED_BYTECODE = ForceGasLimit.deployedBytecode;
+
+describeWithFrontier("Frontier RPC (estimate gas historically)", (context) => {
+	const TEST_CONTRACT_BYTECODE = Storage.bytecode;
+	const TEST_CONTRACT_ABI = Storage.abi as AbiItem[];
+
+	it("estimate gas historically should work", async function () {
+		const contract = new context.web3.eth.Contract(TEST_CONTRACT_ABI);
+
+		this.timeout(15000);
+		const tx = await context.web3.eth.accounts.signTransaction(
+			{
+				from: GENESIS_ACCOUNT,
+				data: TEST_CONTRACT_BYTECODE,
+				value: "0x00",
+				gasPrice: "0x3B9ACA00",
+				gas: "0x100000",
+			},
+			GENESIS_ACCOUNT_PRIVATE_KEY
+		);
+
+		expect(await customRequest(context.web3, "eth_sendRawTransaction", [tx.rawTransaction])).to.include({
+			id: 1,
+			jsonrpc: "2.0",
+		});
+
+		await createAndFinalizeBlock(context.web3);
+		let receipt0 = await context.web3.eth.getTransactionReceipt(tx.transactionHash);
+		let contractAddress = receipt0.contractAddress;
+
+		// Estimate what a sstore set costs at block number 1
+		const SSTORE_SET_DATA = contract.methods
+			.setStorage(
+				"0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc",
+				"0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+			)
+			.encodeABI();
+
+		const ESTIMATE_AT_1 = context.web3.utils.hexToNumber(
+			(
+				await customRequest(context.web3, "eth_estimateGas", [
+					{
+						to: contractAddress,
+						data: SSTORE_SET_DATA,
+					},
+				])
+			).result
+		);
+
+		// Set the storage and create a block
+		const tx1 = await context.web3.eth.accounts.signTransaction(
+			{
+				from: GENESIS_ACCOUNT,
+				to: contractAddress,
+				data: SSTORE_SET_DATA,
+				value: "0x00",
+				gasPrice: "0x3B9ACA00",
+				gas: "0x500000",
+			},
+			GENESIS_ACCOUNT_PRIVATE_KEY
+		);
+		await customRequest(context.web3, "eth_sendRawTransaction", [tx1.rawTransaction]);
+		await createAndFinalizeBlock(context.web3);
+
+		// Estimate what a sstore reset costs at block number 2
+		const ESTIMATE_AT_2 = context.web3.utils.hexToNumber(
+			(
+				await customRequest(context.web3, "eth_estimateGas", [
+					{
+						to: contractAddress,
+						data: SSTORE_SET_DATA,
+					},
+				])
+			).result
+		);
+
+		// SSTORE over an existing storage is cheaper
+		expect(ESTIMATE_AT_2).to.be.lt(ESTIMATE_AT_1);
+
+		// Estimate what a sstore reset costed at block number 1, queried historically
+		const ESTIMATE_AT_1_QUERY = context.web3.utils.hexToNumber(
+			(
+				await customRequest(context.web3, "eth_estimateGas", [
+					{
+						to: contractAddress,
+						data: SSTORE_SET_DATA,
+					},
+					1,
+				])
+			).result
+		);
+
+		// Expect to get the original estimated gas at block 1
+		expect(ESTIMATE_AT_1_QUERY).to.be.eq(ESTIMATE_AT_1);
+	});
+});
 
 describeWithFrontier("Frontier RPC (RPC execution)", (context) => {
 	step("should call with gas limit under block gas limit", async function () {