first pass (#71)

packages/contracts/contracts/test-helpers/Helper_GasMeasurer.sol

+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.7.0;
+
+contract Helper_GasMeasurer {
+    function measureCallGas(
+        address _target,
+        bytes memory _data
+    )
+        public
+        returns ( uint )
+    {
+        uint gasBefore;
+        uint gasAfter;
+
+        uint calldataStart;
+        uint calldataLength;
+        assembly {
+            calldataStart := add(_data,0x20)
+            calldataLength := mload(_data)
+        }
+
+        bool success;
+        assembly {
+            gasBefore := gas()
+            success := call(gas(), _target, 0, calldataStart, calldataLength, 0, 0)
+            gasAfter := gas()
+        }
+        require(success, "Call failed, but calls we want to measure gas for should succeed!");
+
+        return gasBefore - gasAfter;
+    }
+}

packages/contracts/package.json

@@ -19,9 +19,9 @@
     "build:typechain": "buidler typechain",
     "test": "yarn run test:contracts",
     "test:contracts": "buidler test --show-stack-traces",
+    "test:gas": "buidler test \"test/contracts/OVM/execution/OVM_StateManager.gas-spec.ts\" --no-compile --show-stack-traces",
     "lint": "yarn run lint:typescript",
     "lint:typescript": "tslint --format stylish --project .",
-    "lint:fix": "yarn run lint:fix:typescript",
     "lint:fix:typescript": "prettier --config prettier-config.json --write \"buidler.config.ts\" \"{src,test}/**/*.ts\"",
     "clean": "rm -rf ./artifacts ./build ./cache",
     "deploy": "./bin/deploy.js"

packages/contracts/test/contracts/OVM/execution/OVM_StateManager.spec.ts

@@ -6,12 +6,9 @@ import { Contract, ContractFactory, Signer, BigNumber } from 'ethers'
 import _ from 'lodash'
 
 /* Internal Imports */
-import { DUMMY_ACCOUNTS, DUMMY_BYTES32, ZERO_ADDRESS } from '../../../helpers'
+import { DUMMY_ACCOUNTS, DUMMY_BYTES32, ZERO_ADDRESS, EMPTY_ACCOUNT_CODE_HASH, KECCAK_256_NULL } from '../../../helpers'
+
 
-const EMPTY_ACCOUNT_CODE_HASH =
-  '0x00004B1DC0DE000000004B1DC0DE000000004B1DC0DE000000004B1DC0DE0000'
-const KECCAK_256_NULL =
-  '0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470'
 
 describe('OVM_StateManager', () => {
   let signer1: Signer

packages/contracts/test/helpers/constants.ts

@@ -26,6 +26,9 @@ export const NON_ZERO_ADDRESS = makeAddress('11')
 export const VERIFIED_EMPTY_CONTRACT_HASH =
   '0x00004B1DC0DE000000004B1DC0DE000000004B1DC0DE000000004B1DC0DE0000'
 
+export const STORAGE_XOR_VALUE =
+  '0xFEEDFACECAFEBEEFFEEDFACECAFEBEEFFEEDFACECAFEBEEFFEEDFACECAFEBEEF'
+
 export const NUISANCE_GAS_COSTS = {
   NUISANCE_GAS_SLOAD: 20000,
   NUISANCE_GAS_SSTORE: 20000,
@@ -42,3 +45,8 @@ export const STORAGE_XOR =
 export const getStorageXOR = (key: string): string => {
   return toHexString(xor(fromHexString(key), fromHexString(STORAGE_XOR)))
 }
+
+export const EMPTY_ACCOUNT_CODE_HASH =
+  '0x00004B1DC0DE000000004B1DC0DE000000004B1DC0DE000000004B1DC0DE0000'
+export const KECCAK_256_NULL =
+  '0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470'