hardhat-gas-reporter

What is hardhat-gas-reporter?

The hardhat-gas-reporter package is a plugin for Hardhat that generates gas usage reports for smart contract tests. It helps developers understand the gas costs associated with their smart contract functions, which is crucial for optimizing and managing deployment costs.

What are hardhat-gas-reporter's main functionalities?

Gas Usage Reporting

This feature enables gas usage reporting for your Hardhat project. By including the hardhat-gas-reporter plugin in your Hardhat configuration file and setting the appropriate options, you can generate detailed gas usage reports for your smart contract tests.

const { task } = require('hardhat/config');
require('hardhat-gas-reporter');

module.exports = {
  solidity: '0.8.4',
  gasReporter: {
    enabled: true,
    currency: 'USD',
    gasPrice: 21
  }
};

Custom Gas Price and Currency

This feature allows you to customize the gas price and currency for the gas usage reports. By setting the 'currency' and 'gasPrice' options in the configuration, you can tailor the reports to reflect the costs in your preferred currency and gas price.

const { task } = require('hardhat/config');
require('hardhat-gas-reporter');

module.exports = {
  solidity: '0.8.4',
  gasReporter: {
    enabled: true,
    currency: 'EUR',
    gasPrice: 100
  }
};

Code Coverage Integration

This feature integrates gas usage reporting with code coverage tools like solidity-coverage. By including both plugins in your Hardhat configuration, you can generate comprehensive reports that include both gas usage and code coverage metrics.

const { task } = require('hardhat/config');
require('hardhat-gas-reporter');
require('solidity-coverage');

module.exports = {
  solidity: '0.8.4',
  gasReporter: {
    enabled: true,
    currency: 'USD',
    gasPrice: 21
  },
  mocha: {
    timeout: 20000
  }
};

Other packages similar to hardhat-gas-reporter

eth-gas-reporter

eth-gas-reporter is a Mocha reporter for Ethereum test suites that generates gas usage reports. It is similar to hardhat-gas-reporter but is more general-purpose and can be used with various testing frameworks, not just Hardhat.

README

hardhat-gas-reporter

Gas Usage Analytics for Hardhat

• Get gas metrics for method calls and deployments on L1 and L2 by running your test suite.
• Get national currency costs of deploying and using your contract system.
• Output data in multiple formats including text, markdown, reStructuredText and JSON.

Example report

• See markdown format example

Installation

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

Add the following to your hardhat.config.ts:

import "hardhat-gas-reporter"

Configuration

Configuration is optional.

// Example
const config: HardhatUserConfig = {
  gasReporter: {
    currency: 'EUR',
    L1: "polygon",
    coinmarketcap: "abc123...",
  }
}

Usage

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

npx hardhat test

:bulb: Turning the plugin on/off

The enabled option lets you toggle gas reporting on and off using shell environment variables. Tests run faster when the gas reporter is off because fewer calls are made to the client to read data.

const config: HardhatUserConfig = {
  gasReporter: {
    enabled: (process.env.REPORT_GAS) ? true : false
  }
}

:mag: Caveats about Accuracy:

• Gas readings for pure and view methods are only a lower bound of their real world cost. Actual gas usage will depend on the way the methods are called and the storage/memory state of the EVM at the moment of invocation. For more information on this see the excellent summary at wolfio/evm/gas
• L1 gas readings for Arbitrum & OPStack chains are approximations - some variance is expected.
  • Optimism estimates should be within 1% of observed usage on optimistic-etherscan.
  • Arbitrum estimates should be within 10% of observed usage on arbiscan
• The Hardhat client implements the Ethereum Foundation EVM. To get accurate measurements for other EVM-based chains you may need to run your tests against development clients developed specifically for those networks.

Options

• Option setups for common and advanced use cases can be seen in the Config Examples docs.
• Get a free tier Coinmarketcap API key if you want price data
• (Also) get free tier Etherscan API keys if you want price data for Ethereum mainnet or an L2 network.

Options	Type	Default	Description
currency	string	USD	National currency to represent gas costs in. Exchange rates are loaded at runtime from the coinmarketcap api. Available currency codes can be found here
coinmarketcap	string	-	API key to use when fetching live token price data
enabled	bool	true	Produce gas reports with hardhat test
excludeAutoGeneratedGetters	bool	false	Exclude solc generated public state vars when reporting gas for pure and view methods. (Incurs a performance penalty on test startup when true) ⚠️ SLOW ⚠️
excludeContracts	string[]	[]	Names of contracts to exclude from report. Ex: ["MyContract"]
includeIntrinsicGas	bool	true	Include standard 21_000 + calldata bytes overhead in method gas usage data. (Setting to false can be useful for modelling contract infra that will never be called by an EOA)
L1	string	ethereum	Auto-configure reporter to emulate an L1 network. (See supported networks)
L2	string	-	Auto-configure reporter to emulate an L2 network (See supported networks)
L1Etherscan	string	-	API key to use when fetching live gasPrice and baseFee data from an L1 network. (Optional, see Supported Networks)
L2Etherscan	string	-	API key to use when fetching live gasPrice and blobBaseFee data from an L2 network (Optional, see Supported Networks)
offline	bool	false	Turn off remote calls to fetch data
optimismHardfork	string	ecotone	Optimism hardfork to emulate L1 & L2 gas costs for.
proxyResolver	Class	-	User-defined class which helps reporter identify contract targets of proxied calls. (See Advanced Usage)
remoteContracts	Array	-	List of forked-network deployed contracts to track execution costs for.(See Advanced Usage)
reportPureAndViewMethods	bool	false	Track gas usage for methods invoked via eth_call. (Incurs a performance penalty that can be significant for large test suites)
trackGasDeltas	bool	false	Track and report changes in gas usage between test runs. (Useful for gas golfing)
:high_brightness: DISPLAY
currencyDisplayPrecision	number	2	Decimal precision to show nation state currency costs in
darkMode	bool	false	Use colors better for dark backgrounds when printing to stdout
forceTerminalOutput	bool	false	Write to terminal even when saving output to file
forceTerminalOutputFormat	string	-	Table format to output forced terminal output in ("legacy" / "terminal" / "markdown")
noColors	bool	false	Omit terminal color in output
reportFormat	string	terminal	Report formats ("legacy" / "terminal" / "markdown")
showMethodSig	bool	false	Display the complete function signature of methods. (Useful if you have overloaded methods)
showUncalledMethods	bool	false	List all methods and deployments, even if no transactions were recorded for them
suppressTerminalOutput	bool	false	Skip writing the table to stdout. (Useful if you only want to write JSON to file)
:floppy_disk: OUTPUT
includeBytecodeInJSON	bool	false	Include bytecode and deployedBytecode blobs in JSON output
outputFile	string	-	Relative path to a file to output text table to (instead of stdout)
outputJSONFile	string	-	Relative path to a file to output gas data in JSON format to. (See Advanced Usage)
outputJSON	bool	false	Write options, methods, deployment data in JSON format to file. (See Advanced Usage)
rst	bool	false	Output with a reStructured text code-block directive. (Useful if you want to include report in ReadTheDocs or Sphinx docs)
rstTitle	string	-	Title for reStructured text header
:mag: LOW-LEVEL CONFIG
gasPrice	number	-	Gwei price per gas unit (Ex: 25). By default, this is fetched from live network when coinmarketcap option is defined
baseFee	number	-	Gwei base fee per gas unit used to calculate L1 calldata costs for L2 transactions (Ex: 25). By default, this is fetched from live network when L2 & coinmarketcap options are defined
baseFeePerByte	number	-	Gwei fee per byte used to calculate L1 calldata costs for Arbitrum transactions (Ex: 25). See arbitrum gas estimation docs for details. By default, this is fetched from live network when L2 is set to 'arbitrum' & coinmarketcap options are defined
blobBaseFee	number	-	Gwei blob base fee per gas unit used to calculate post-EIP-7516 L1 calldata costs for L2 transactions (Ex: 25). By default, this is fetched from live network when L2 & coinmarketcap options are defined
blobBaseFeeApi	string	-	URL to fetch live execution network blob base fee from. (By default, this is auto-configured based on the L1 or L2 setting)
gasPriceApi	string	-	URL to fetch live execution network gas price from. (By default, this is auto-configured based on the L1 or L2 setting)
getBlockApi	string	-	URL to fetch L1 block header from when simulating L2. (By default, this is auto-configured based on the L2 setting)
opStackBaseFeeScalar	number	-	Scalar applied to L1 base fee when calculating L1 data cost (see Advanced Usage)
opStackBlobBaseFeeScalar	number	-	Scalar applied to L1 blob base fee when calculating L1 data cost (see Advanced Usage)
token	string	-	Network token gas fees are denominated in (ex:"ETH"). (By default, this is auto-configured based on the L1 or L2 setting)
tokenPrice	string	-	Network token price per nation state currency unit. (To denominate costs in network token set this to "1")

Utility Tasks

The plugin also provides additional utility commands for managing gas reporter output

hhgas:merge

Merges several JSON formatted gas reports into a single object. This is useful if you're post-processing the data and running your tests in a parallelized CI environment.

Usage

npx hardhat hhgas:merge "gasReporterOutput-*.json"

Supported Networks

API keys for the networks this plugin auto-configures via the L1 and L2 options are available from the links below. In many cases these aren't required - you'll only need to set them if you start seeing rate-limit warnings.

:warning: UPDATE: Etherscan now requires api keys to fetch both L1 (Ethereum Mainnet) and L2 gas price data. (An example config can be found here)

L2

• arbitrum (live baseFeePerByte prices require an L2 API key )
• base (live blobBaseFee prices require an L2 API key)
• optimism (live blobBaseFee prices require an L2 API key)

L1

• ethereum (gasPrice and baseFee prices require an API key)
• polygon
• binance
• fantom
• moonbeam
• moonriver
• gnosis
• avalanche

Funding

You can support hardhat-gas-reporter via DRIPS, a public goods protocol that helps you direct funding to packages in your dependency tree.