hardhat-gas-reporter

eth-gas-reporter plugin for hardhat.

What

A Mocha reporter for Ethereum test suites:

• Gas usage per unit test.
• Metrics for method calls and deployments.
• National currency costs of deploying and using your contract system.

Example report

Installation

npm install hardhat-gas-reporter --save-dev

And add the following to your hardhat.config.js:

require("hardhat-gas-reporter");

Or, if you are using TypeScript, add this to your hardhat.config.ts:

import "hardhat-gas-reporter"

Looking for buidler-gas-reporter docs? They moved here...

Configuration

Configuration is optional.

module.exports = {
  gasReporter: {
    currency: 'CHF',
    gasPrice: 21
  }
}

💡 Pro Tips

Turning the plugin on/off

The options include an enabled key that lets you toggle gas reporting on and off using shell environment variables. When enabled is false, mocha's (faster) default spec reporter is used. Example:

module.exports = {
  gasReporter: {
    enabled: (process.env.REPORT_GAS) ? true : false
  }
}

Migrating from Truffle

If you already have eth-gas-reporter installed in your project, make sure you uninstall it before adding this plugin. hardhat-gas-reporter manages eth-gas-reporter as a dependency and having multiple versions in your lockfile can stop the reporter from working correctly.

Usage

This plugin overrides the built-in test task. Gas reports are generated by default with:

npx hardhat test

Options

⚠️ CoinMarketCap API change ⚠️

Beginning March 2020, CoinMarketCap requires an API key to access currency market price data. The reporter uses an unprotected free tier key by default (10k reqs/mo). You can get your own API key here and set it with the coinmarketcap option.

In order to retrieve the gas price of a particular blockchain, you can configure the token and gasPriceApi (API key rate limit may apply).

NOTE: HardhatEVM and ganache-cli implement the Ethereum blockchain. To get accurate gas measurements for other chains you may need to run your tests against development clients developed specifically for those networks.

token and gasPriceApi options example

These APIs have rate limits. Depending on the usage, it might require an API Key.

NB: Any gas price API call which returns a JSON-RPC response formatted like this is supported: {"jsonrpc":"2.0","id":73,"result":"0x6fc23ac00"}.

Documentation

Other useful documentation can be found at eth-gas-reporter

Parallelization

This plugin also adds a Hardhat Task for merging several gasReporterOutput.json files, which are generated by eth-gas-reporter when running your tests with in parallelized jobs in CI.

To use the task you just have to give it the filepaths or a glob pattern pointing to all of the reports:

npx hardhat gas-reporter:merge 'gasReporterOutput-*.json'

Here is an example config.yml file used by CircleCI to run the tests on parallel first, and then merge the reports

version: 2.1

jobs:
  test:
    docker:
      - image: circleci/node:14.15.1-stretch
    parallelism: 8
    steps:
      - attach_workspace:
          at: .
      - run:
          name: Run tests
          command: |
            circleci tests glob 'test/**/*.spec.ts' |
            circleci tests split |
            xargs npx hardhat test
      - run:
          name: Save gas report
          command: |
            mv gasReporterOutput.json ./gasReporterOutput-$CIRCLE_NODE_INDEX.json
      - persist_to_workspace:
          root: .
          paths:
            - gasReporterOutput-*.json
  test-gas-report:
    docker:
      - image: circleci/node:14.15.1-stretch
    steps:
      - checkout
      - attach_workspace:
          at: .
      - run:
          name: Upload gas reports
          command: |
            npx hardhat gas-reporter:merge gasReporterOutput-*.json
            npx codechecks codechecks.unit.yml
      - store_artifacts:
          path: gasReporterOutput.json

workflows:
  workflow-all:
    jobs:
      - test
      - test-gas-report:
          requires:
            - test