Add mainnet fork usage behind feature flag

- translate between chainID 1337<>1 on modifying transactions
- use env variables for url and chainID

Using a prodlike environment — running our code agains a mainnet fork
is valuable so we can test contract interaction and dApps integrations
that are deployed on mainnet.

For the deployed dApps to work normaly they need to see chainID 1.
Otherwise it will trigger a "sleect a supported network" response.

Hardhat mainnet fork freezes atm if the chainID is set to 1 but works
well with chainID 1337.

The soution is to translate between them when writing to the fork.

.env.defaults

@@ -13,3 +13,7 @@ HIDE_IMPORT_LEDGER=false
 GAS_PRICE_POOLING_FREQUENCY=120
 ETHEREUM_NETWORK=mainnet
 PERSIST_UI_LOCATION=false
+USE_MAINNET_FORK=false
+MAINNET_FORK_URL="http://127.0.0.1:8545"
+MAINNET_FORK_CHAIN_ID=1337
+

background/constants/networks.ts

@@ -44,6 +44,13 @@ export const BITCOIN: Network = {
   family: "BTC",
 }
 
+export const FORK: EVMNetwork = {
+  name: "Ethereum",
+  baseAsset: ETH,
+  chainID: process.env.MAINNET_FORK_CHAIN_ID ?? "1337",
+  family: "EVM",
+}
+
 export const EVM_MAIN_NETWORKS = [ETHEREUM]
 
 export const EVM_TEST_NETWORKS = [ROPSTEN, RINKEBY, GOERLI, KOVAN]

background/features/features.ts

@@ -7,3 +7,4 @@ export const HIDE_IMPORT_DERIVATION_PATH =
 export const HIDE_CREATE_PHRASE = process.env.HIDE_CREATE_PHRASE === "true"
 export const HIDE_IMPORT_LEDGER = process.env.HIDE_IMPORT_LEDGER === "true"
 export const PERSIST_UI_LOCATION = process.env.PERSIST_UI_LOCATION === "true"
+export const USE_MAINNET_FORK = process.env.USE_MAINNET_FORK === "true"

background/redux-slices/transaction-construction.ts

@@ -1,11 +1,13 @@
 import { createSlice, createSelector } from "@reduxjs/toolkit"
 import Emittery from "emittery"
+import { FORK } from "../constants"
 import {
   EXPRESS,
   INSTANT,
   MAX_FEE_MULTIPLIER,
   REGULAR,
 } from "../constants/network-fees"
+import { USE_MAINNET_FORK } from "../features/features"
 
 import {
   BlockEstimate,
@@ -96,6 +98,10 @@ export const updateTransactionOptions = createBackgroundAsyncThunk(
 export const signTransaction = createBackgroundAsyncThunk(
   "transaction-construction/sign",
   async (request: SignatureRequest) => {
+    if (USE_MAINNET_FORK) {
+      request.transaction.chainID = FORK.chainID
+    }
+
     await emitter.emit("requestSignature", request)
   }
 )

background/services/chain/utils.ts

@@ -15,6 +15,8 @@ import {
   ConfirmedEVMTransaction,
 } from "../../networks"
 import { FungibleAsset } from "../../assets"
+import { USE_MAINNET_FORK } from "../../features/features"
+import { FORK } from "../../constants"
 
 /**
  * Parse a block as returned by a polling provider.
@@ -132,7 +134,7 @@ export function ethersTransactionFromSignedTransaction(
     from: tx.from,
     data: tx.input || "",
     type: tx.type,
-    chainId: parseInt(tx.network.chainID, 10),
+    chainId: parseInt(USE_MAINNET_FORK ? FORK.chainID : tx.network.chainID, 10),
     value: BigNumber.from(tx.value),
     gasLimit: BigNumber.from(tx.gasLimit),
   }

background/services/keyring/index.ts

@@ -20,9 +20,9 @@ import {
 } from "../../types"
 import { EIP1559TransactionRequest, SignedEVMTransaction } from "../../networks"
 import BaseService from "../base"
-import { ETH, MINUTE } from "../../constants"
+import { ETH, FORK, MINUTE } from "../../constants"
 import { ethersTransactionRequestFromEIP1559TransactionRequest } from "../chain/utils"
-import { HIDE_IMPORT_LEDGER } from "../../features/features"
+import { HIDE_IMPORT_LEDGER, USE_MAINNET_FORK } from "../../features/features"
 import { AddressOnNetwork } from "../../accounts"
 
 export const MAX_KEYRING_IDLE_TIME = 60 * MINUTE
@@ -444,7 +444,7 @@ export default class KeyringService extends BaseService<Events> {
       blockHash: null,
       blockHeight: null,
       asset: ETH,
-      network,
+      network: USE_MAINNET_FORK ? FORK : network,
     }
     if (HIDE_IMPORT_LEDGER) {
       this.emitter.emit("signedTx", signedTx)

background/services/signing/index.ts

@@ -11,6 +11,8 @@ import BaseService from "../base"
 import { ServiceCreatorFunction, ServiceLifecycleEvents } from "../types"
 import ChainService from "../chain"
 import { SigningMethod } from "../../redux-slices/signing"
+import { USE_MAINNET_FORK } from "../../features/features"
+import { FORK } from "../../constants"
 
 type SigningErrorReason = "userRejected" | "genericError"
 type ErrorResponse = {
@@ -138,7 +140,9 @@ export default class SigningService extends BaseService<Events> {
     transactionRequest: EIP1559TransactionRequest,
     signingMethod: SigningMethod
   ): Promise<SignedEVMTransaction> {
-    const network = this.chainService.resolveNetwork(transactionRequest)
+    const network = USE_MAINNET_FORK
+      ? FORK
+      : this.chainService.resolveNetwork(transactionRequest)
     if (typeof network === "undefined") {
       throw new Error(`Unknown chain ID ${transactionRequest.chainID}.`)
     }