Made a test for reading block gas limit in contracts

tests/package.json

@@ -19,6 +19,7 @@
     "mocha": "^8.3.2",
     "mocha-steps": "^1.3.0",
     "rimraf": "^3.0.2",
+    "solc": "^0.8.3",
     "ts-node": "9.1",
     "typescript": "^3.9.6",
     "web3": "^1.3.5"

tests/tests/constants/testContracts.ts

@@ -1,4 +1,33 @@
 import { AbiItem } from "web3-utils";
+import solc from "solc";
+
+export function compileSolidity(contractContent: string, contractName: string = "Test") {
+  let result = JSON.parse(
+    solc.compile(
+      JSON.stringify({
+        language: "Solidity",
+        sources: {
+          "main.sol": {
+            content: contractContent,
+          },
+        },
+        settings: {
+          outputSelection: {
+            "*": {
+              "*": ["*"],
+            },
+          },
+        },
+      })
+    )
+  );
+
+  const contract = result.contracts["main.sol"][contractName];
+  return {
+    bytecode: "0x" + contract.evm.bytecode.object,
+    contract,
+  };
+}
 
 // Solidity: contract test {function multiply(uint a) public pure returns(uint d) {return a * 7;}}
 export const TEST_CONTRACT_BYTECODE =
@@ -201,6 +230,26 @@ export const FINITE_LOOP_CONTRACT_ABI = [
   },
 ] as AbiItem[];
 
+// Gas limit test contract
+
+export const contractSourceBlockGasLimit = `
+pragma solidity >=0.8.0;
+
+// Docs I'm following to get these properties
+// https://docs.soliditylang.org/en/v0.8.2/units-and-global-variables.html
+
+contract CheckBlockGasLimit {
+  // This one is broken (evaluates to 0)
+  uint public gas;
+  // This one works
+  uint public chainid;
+
+  constructor() {
+    gas = block.gaslimit;
+    chainid = block.chainid;
+  }
+}`;
+
 export const ERC20_BYTECODE =
   "0x608060405234801561001057600080fd5b50610024336202616061002960201b60201c565b610274565b600073ff" +
   "ffffffffffffffffffffffffffffffffffffff168273ffffffffffffffffffffffffffffffffffffffff1614156100" +

tests/tests/test-block.ts

@@ -1,8 +1,20 @@
 import { expect } from "chai";
 import { step } from "mocha-steps";
-import { contractCreation, GENESIS_ACCOUNT } from "./constants";
-
-import { createAndFinalizeBlock, describeWithMoonbeam, fillBlockWithTx } from "./util";
+import {
+  compileSolidity,
+  contractCreation,
+  contractSourceBlockGasLimit,
+  GENESIS_ACCOUNT,
+  GENESIS_ACCOUNT_PRIVATE_KEY,
+} from "./constants";
+
+import {
+  createAndFinalizeBlock,
+  customRequest,
+  deployContractManualSeal,
+  describeWithMoonbeam,
+  fillBlockWithTx,
+} from "./util";
 
 describeWithMoonbeam("Moonbeam RPC (Block)", `simple-specs.json`, (context) => {
   let previousBlock;
@@ -198,4 +210,17 @@ describeWithMoonbeam("Moonbeam RPC (Block)", `simple-specs.json`, (context) => {
     let { txPassed } = await fillBlockWithTx(context, 8193, contractCreation);
     expect(txPassed).to.eq(0);
   });
+
+  it("should be able to access block gas lmit within a contract", async function () {
+    this.timeout(15000);
+    const contractCompiled = compileSolidity(contractSourceBlockGasLimit, "CheckBlockGasLimit");
+    const contract = await deployContractManualSeal(
+      context.polkadotApi,
+      context.web3,
+      contractCompiled.bytecode,
+      contractCompiled.contract.abi
+    );
+    console.log("gas", await contract.methods.gas().call());
+    expect((await contract.methods.gas().call()) !== "0").to.eq(true);
+  });
 });