How to change baseFeePerGas in testing

[RippleLeaf]

I am testing a smart contract on a local development chain. The smart contract runs normally with ganache CLI 6.12.2 (ganache-core: 2.13.2). After updating ganache to the latest version (7.3.2), with truffle test it gives the following error:

Error: while migrating Migrations: Returned error: VM Exception while processing transaction: Transaction's maxFeePerGas (0) is less than the block's baseFeePerGas (875000000) (vm hf=london -> block -> tx)

May I know if there is a way to set baseFeePerGas=0 to zero for testing? I have tried setting it in truffle-config.js and in the command line but neither worked, and I didn't find any online document about how to set it.

[RippleLeaf]

@MicaiahReid Hi, I opened this discussion question here. Thank you for your reply in this issue!

[MicaiahReid]

Thanks for opening this here! I'm sure others will have the same question, so it's nice to have it formally answered where others can find it!

[MicaiahReid]

@RippleLeaf We don't currently have a way to set the baseFeePerGas, but we do have an issue for it, so you can expect to see this feature in the near(ish) future.

In terms of workarounds, you have a few options:

1. Update your tests to set appropriate an gasPrice on your transactions. However, I obviously don't know the details of what you're working on, so this may not be feasible or helpful.
2. Start Ganache with the --chain.hardfork berlin option. This will use berlin hardfork rules for the chain, which was before blocks had a baseFeePerGas.
3. Use evm_mine to lower the baseFeePerGas of blocks. Every time a block is mined, the baseFeePerGas is either lowered or raised based off of how full the previous block is. The max that the baseFeePerGas can be raised or lowered from one block to the next is 12%. So if you used evm_mine to mine 125 blocks on startup, the baseFeePerGas would lower from 875000000 WEI to pretty close to 0 WEI.

[RippleLeaf]

Thank you very much! I run with the berlin hardfork and it works fine now.

The new version of ganache somehow also solved another problem I had earlier - I guess it was something related to memory overflow, but I didn't find the exact reason. Now the line causing transaction revert in the earlier version of ganache just works fine... I still don't know why but it is good! Thank you for your help again!

[staminna]

@MicaiahReid Can you elaborate the commands/files need to be adjusted to set the evm_mine and baseFeePerGas? I am not sure how to calculate values ideal for the app. I was able to do two transactions locally until it exhausted the gas on my Ganache (localhost).

[MicaiahReid]

Hi @staminna! To clarify, this method is only really helpful if you're trying to lower a block's baseFeePerGas, and not to an exact value.
Something like this would repeatedly mine an empty block until the baseFeePerGas is lowered below a desired value:

  const provider = ganache.provider(options);
  const DESIRED_BASE_FEE =  100000000; // set to whatever you want
  let block;
  do {
    block = await provider.request({
      method: "eth_getBlockByNumber",
      params: ["latest", true]
    });
    console.log(block.baseFeePerGas);
    await provider.request({
      method: "evm_mine",
      params: []
    });
  } while (parseInt(block.baseFeePerGas) > DESIRED_BASE_FEE);