Mainnet forking stopped working after 2.7.1

[pdyraga]

tl;dr;

When trying to hardhat_reset on mainnet fork, I am getting TypeError: config.chains.has is not a function error. The code worked fine on hardhat version 2.7.1 and started failing once we updated to 2.8.4. Updating to the most recent version - 2.9.3 as of now - does not help.

How to reproduce

Option 1

1. Check out https://github.com/threshold-network/solidity-contracts
2. Try running FORKING_URL=https://eth-mainnet.alchemyapi.io/v2/<id> yarn test:system
3. Observe TypeError: config.chains.has is not a function error

If you want to dive deeper: Go back in the history, to commit f129e209ff70e74d37e78d4db6d7987950844bb6, just before the version was updated you will see the tests passing. If you go to commit b8d198e9ec0e0adc91d35ad322d2815ad850a2b5 where the version was updated, you will see the tests failing.

Option 2

1. Check out https://github.com/keep-network/coverage-pools
2. Run FORKING_URL=https://eth-mainnet.alchemyapi.io/v2/<id> yarn test:system
3. Observe tests passing
4. Edit package.json and update Hardhat to the most recent version
5. Run FORKING_URL=https://eth-mainnet.alchemyapi.io/v2/<id> yarn test:system
6. Observe tests failing with TypeError: config.chains.has is not a function

Option 3

Try this piece of code with the most recent (2.9.3) hardhat version and config from either
https://github.com/threshold-network/solidity-contracts/blob/main/hardhat.config.ts
or
https://github.com/keep-network/coverage-pools/blob/main/hardhat.config.ts

You will see the test failing with TypeError: config.chains.has is not a function when trying to hardhat_reset.

const hre = require("hardhat")

describe.only("Forking test", () => {
  async function resetFork() {
    await hre.network.provider.request({
      method: "hardhat_reset",
      params: [
        {
          forking: {
            jsonRpcUrl: "https://eth-mainnet.alchemyapi.io/v2/<id>",
            blockNumber: 13619810,
          },
        },
      ],
    })
  }

  before(async () => {
    await resetFork()
  })

  it("should work", async () => {
    console.log("ok")
  })
})

  1) Forking test
       "before all" hook for "should work":
     TypeError: config.chains.has is not a function
      at Function.create (node_modules/hardhat/src/internal/hardhat-network/provider/node.ts:199:25)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)
      at async HardhatNetworkProvider._init (node_modules/hardhat/src/internal/hardhat-network/provider/provider.ts:250:28)
      at async HardhatNetworkProvider._send (node_modules/hardhat/src/internal/hardhat-network/provider/provider.ts:191:5)
      at async HardhatNetworkProvider.request (node_modules/hardhat/src/internal/hardhat-network/provider/provider.ts:117:18)
      at async resetFork (test/system/staking.test.js:5:5)
      at async Context.<anonymous> (test/system/staking.test.js:19:5)

[github-actions]

This issue is also being tracked on Linear.

We use Linear to manage our development process, but we keep the conversations on Github.

LINEAR-ID: 146409a3-4675-476c-ba59-b12341a442d6

[fvictorio]

Ugh, this one was hard. Thanks for reporting, @pdyraga.

I think the root of the issue is here:

https://github.com/keep-network/hardhat-local-networks-config/blob/964729beeb28115e143de61d6a99ece74eafb14b/src/index.ts#L21

The Hardhat Network config has a chains property, which is a Map. But if you use deepmerge with a map, it gets converted to an object (and you lose its contents):

> deepmerge({}, {a: new Map([[1, 1]])})
{ a: {} }

I don't know what's the right solution here. There is an open issue about this in the deepmerge repo and the author created an alternative that seems to support maps and sets, maybe that helps?

[fvictorio]

I'm going to close this issue now because there's not much we can do here. Converting the chains Map to a plain object is a breaking change (and it would take a significant amount of work), so we won't be able to do it. But please let me know if I can help you in any way with this!

[pdyraga]

Thanks @fvictorio. I confirmed that after removing a reference to hardhat-local-networks-config-plugin from our config (threshold-network/solidity-contracts#102) tests on forked mainnet passed. I opened an issue in the plugin repo: facuspagnuolo/hardhat-local-networks-config-plugin#7