How to get the gas costs of a reversed transaction when testing (with Chai / ethers.js / Hardhat)?

Question

Does anyone know how to get the gas costs of a reversed transaction when testing with Hardhat / Chai?

I found out I can get the receipt object of a transaction, which holds the required data to calculate the total gas costs, like so:

const transaction = contract.connect(account).withdraw(); 
const receipt = await transaction.wait();
const transactionCosts = receipt.gasUsed.mul(
  receipt.effectiveGasPrice
);

But now I have a transaction that gets reverted, for which I am also testing. Code:

await expect(
  contract.connect(account).withdraw()
).to.be.revertedWith("Ownable: caller is not the owner");

Does anyone know how I get the gas costs (like in the first example) of the transaction in the second example?

Answer 1

I've figured out a way to do this, althought I wonder if there isn't an easier way.

    // Get latest transaction hash
    const latestBlock = await ethers.provider.getBlock("latest");
    const latestTXHash = latestBlock.transactions.at(-1);
    // Get latest transaction receipt object
    const latestTXReceipt = await ethers.provider.getTransactionReceipt(
      latestTXHash
    );
    // Determine latest transaction gas costs
    const latestTXGasUsage = latestTXReceipt.gasUsed;
    const latestTXGasPrice = latestTXReceipt.effectiveGasPrice;
    const latestTXGasCosts = latestTXGasUsage.mul(latestTXGasPrice);