Sim backend returns 1 for SuggestGasPrice not Basefee

[MariusVanDerWijden]

// SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated
// chain doesn't have miners, we just return a gas price of 1 for any call.
func (b *SimulatedBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
	return big.NewInt(1), nil
}

-> Does not work post 1559, just return pendingBlock.Header.Basefee or something

[Sparty]

Can I work on this?

[MariusVanDerWijden]

Sure!

[MariusVanDerWijden]

fixed

[deitch]

I just stumbled across this. Given that this is a simulated backend, how is the original base fee set? I am doing a simple chain creation and getting a base fee of some absurdly high number, something like 875000000.

What particularly threw me off was the function description:

SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated chain doesn't have miners, we just return a gas price of 1 for any call.

That definitely is not 1.

I am not doing anything fancy, as simple as:

	privateKey, err := crypto.GenerateKey()
	if err != nil {
		return nil, err
	}

	auth, err := bind.NewKeyedTransactorWithChainID(privateKey, big.NewInt(1337))
	if err != nil {
		return nil, err
	}

	balance := new(big.Int)
	balance.SetString("10000000000000000000", 10) // 10 eth in wei

	address := auth.From
	genesisAlloc := map[common.Address]core.GenesisAccount{
		address: {
			Balance: balance,
		},
	}

	blockGasLimit := uint64(4712388)
	client := backends.NewSimulatedBackend(genesisAlloc, blockGasLimit)

Stepping through, it looks like it creates it here as part of NewSimulatedBackendWithDatabase, specifically as part of the core.Genesis, which has an option to set the BaseFee (but is unused here), which then is inherited in core.NewBlockChain(). I think.

func NewSimulatedBackendWithDatabase(database ethdb.Database, alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
	genesis := core.Genesis{Config: params.AllEthashProtocolChanges, GasLimit: gasLimit, Alloc: alloc}
	genesis.MustCommit(database)
	blockchain, _ := core.NewBlockChain(database, nil, genesis.Config, ethash.NewFaker(), vm.Config{}, nil, nil)

	backend := &SimulatedBackend{
		database:   database,
		blockchain: blockchain,
		config:     genesis.Config,
		events:     filters.NewEventSystem(&filterBackend{database, blockchain}, false),
	}
	backend.rollback(blockchain.CurrentBlock())
	return backend
}

Is this a bug in how SuggestGasPrice() works? Am I setting up the chain incorrectly? Or is it that it needs some option that is missing?