How to estimate gas of a receive method() in truffle

[SD170]

I know that if my contract has a name() method. I can go to the truffle console and try

contractInstance.name.estimateGas()

and this will give the estimate gas for that method.

but what if have a receive method inside my contract to take ether:

receive() external payable {
} 

and I wanna know it's gas. Then what is the correct syntax?

I've tried:

contractInstance.estimateGas()

as I thought as receive is the default function for ether payment. But didn't work.

contractInstance.receive.estimateGas()

this doesn't work either.

can I get some help?

[haltman-at]

Hi! Unfortunately, there's no convenient way to do this at the moment. Doing instance.estimateGas({}) would be a good way to do this if we supported it, but unfortunately at the moment we don't... I've put up an issue for this, #5374, and hopefully we can get that done soon.

In the meantime, you can do this manually using web3.js. If you have your contract instance, you can do

web3.eth.estimateGas({ from: accounts[0], to: instance.address })

in order to perform the gas estimation that you want. You can of course also include a value parameter if you want to send some number of wei, in case that affects things.

Hope that's helpful!

[SD170]

Hi, @haltman-at thanks for the reply. The thing is, I've been using truffle for some time. And I was wondering if I could contribute some. If it's okay I can try adding this feature (instance.estimateGas() for the fallback/receive methods), If I get some guide.

Should I go to the issue you've created and make this comment there? or I can try to add the feature and do a PR directly?
I know you're a maintainer of this project, and I'm kinda new to open source, so I thought of asking you.

[haltman-at]

You could make a PR, but I have to warn you, the code for @truffle/contract is quite hairy...

[SD170]

Thanks for the heads up :) I'll try. Otherwise, I'll try to contribute with something easier.

[haltman-at]

FWIW, I've put up PR #5426 to address this! Hopefully it gets merged and released soon.

[SD170]

Great man. I saw the code. I also hope it gets merged soon :)