Enable London for hardhat network (gnosis/gp-v2-contracts#774)

* Bump hardhat from 2.5.0 to 2.6.0

Bumps [hardhat](https://github.com/nomiclabs/hardhat) from 2.5.0 to 2.6.0.
- [Release notes](https://github.com/nomiclabs/hardhat/releases)
- [Commits](NomicFoundation/hardhat@hardhat-core-v2.5.0...hardhat-core-v2.6.0)

---
updated-dependencies:
- dependency-name: hardhat
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

* Update tests to work in London

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

hardhat.config.ts

@@ -43,6 +43,7 @@ if (["rinkeby", "mainnet"].includes(argv.network) && INFURA_KEY === undefined) {
 }
 
 const mocha: MochaOptions = {};
+let initialBaseFeePerGas: number | undefined = undefined;
 switch (MOCHA_CONF) {
   case undefined:
     break;
@@ -53,6 +54,9 @@ switch (MOCHA_CONF) {
     // - coverage compiles without optimizer and, unlike Waffle, hardhat-deploy
     //   strictly enforces the contract size limits from EIP-170
     mocha.grep = /^(?!E2E|Task)/;
+    // Note: unit is Wei, not GWei. This is a workaround to make the coverage
+    // tool work with the London hardfork.
+    initialBaseFeePerGas = 1;
     break;
   case "ignored in coverage":
     mocha.grep = /^E2E|Task/;
@@ -91,6 +95,7 @@ export default {
   networks: {
     hardhat: {
       blockGasLimit: 12.5e6,
+      initialBaseFeePerGas,
     },
     mainnet: {
       ...sharedNetworkConfig,

package.json

@@ -58,7 +58,7 @@
     "ethereum-waffle": "^3.4.0",
     "ethers": "^5.4.4",
     "globby": "^11.0.4",
-    "hardhat": "^2.5.0",
+    "hardhat": "^2.6.0",
     "hardhat-deploy": "^0.7.3",
     "hardhat-gas-reporter": "^1.0.4",
     "prettier": "^2.3.2",

src/ts/settlement.ts

@@ -115,6 +115,13 @@ export interface TradeExecution {
 
 /**
  * Order refund data.
+ *
+ * Note: after the London hardfork (specifically the introduction of EIP-3529)
+ * order refunds have become meaningless as the refunded amount is less than the
+ * gas cost of triggering the refund. The logic surrounding this feature is kept
+ * in order to keep full test coverage and in case the value of a refund will be
+ * increased again in the future. However, order refunds should not be used in
+ * an actual settlement.
  */
 export interface OrderRefunds {
   /** Refund storage used for order filled amount */

yarn.lock

@@ -304,10 +304,10 @@
     "@ethereumjs/common" "^2.4.0"
     ethereumjs-util "^7.1.0"
 
-"@ethereumjs/vm@^5.5.0":
-  version "5.5.0"
-  resolved "https://registry.yarnpkg.com/@ethereumjs/vm/-/vm-5.5.0.tgz#d389c5792320ef28c51366a643b8ab9d64e10a31"
-  integrity sha512-h6Kr6WqKUP8nVuEzCWPWEPrC63v7HFwt3gRuK7CJiyg9S0iWSBKUA/YVD4YgaSVACuxUfWaOBbwV5uGVupm5PQ==
+"@ethereumjs/vm@^5.5.2":
+  version "5.5.2"
+  resolved "https://registry.yarnpkg.com/@ethereumjs/vm/-/vm-5.5.2.tgz#918a2c1000aaa9fdbe6007a4fdc2c62833122adf"
+  integrity sha512-AydZ4wfvZAsBuFzs3xVSA2iU0hxhL8anXco3UW3oh9maVC34kTEytOfjHf06LTEfN0MF9LDQ4ciLa7If6ZN/sg==
   dependencies:
     "@ethereumjs/block" "^3.4.0"
     "@ethereumjs/blockchain" "^5.4.0"
@@ -5500,16 +5500,16 @@ hardhat-gas-reporter@^1.0.4:
     eth-gas-reporter "^0.2.20"
     sha1 "^1.1.1"
 
-hardhat@^2.5.0:
-  version "2.5.0"
-  resolved "https://registry.yarnpkg.com/hardhat/-/hardhat-2.5.0.tgz#0a10bf85d9b2c3c7c12cfa4e35454296c670c054"
-  integrity sha512-S5CWcmiFZlFF2qFGyf5LlgVnJDXwTs5UBKU3GPQCjsUD3NAIWzXr/4xDSij3YWdg751axgLiKAJM01cHcxGb7A==
+hardhat@^2.6.0:
+  version "2.6.0"
+  resolved "https://registry.yarnpkg.com/hardhat/-/hardhat-2.6.0.tgz#a00a44d36559a880c170dca6363cc33f7545364b"
+  integrity sha512-NEM2pe11QXWXB7k49heOLQA9vxihG4DJ0712KjMT9NYSZgLOMcWswJ3tvn+/ND6vzLn6Z4pqr2x/kWSfllWFuw==
   dependencies:
     "@ethereumjs/block" "^3.4.0"
     "@ethereumjs/blockchain" "^5.4.0"
     "@ethereumjs/common" "^2.4.0"
     "@ethereumjs/tx" "^3.3.0"
-    "@ethereumjs/vm" "^5.5.0"
+    "@ethereumjs/vm" "^5.5.2"
     "@ethersproject/abi" "^5.1.2"
     "@sentry/node" "^5.18.1"
     "@solidity-parser/parser" "^0.11.0"