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npm version Build Status Codechecks buidler

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.
  • CI integration with codechecks
  • Simple installation for Truffle and Buidler

Example output

Screen Shot 2019-06-24 at 4 54 47 PM

Installation and Config


npm install --save-dev eth-gas-reporter
/* truffle-config.js */
module.exports = {
  networks: { ... },
  mocha: {
    reporter: 'eth-gas-reporter',
    reporterOptions : { ... } // See options below


npm install --save-dev buidler-gas-reporter
/* buidler.config.js */

module.exports = {
  networks: { ... },
  gasReporter: { ... } // See options below


This reporter should work with any build platform that uses Mocha and connects to an Ethereum client running as a separate process. There's more on advanced use cases here.

Continuous Integration (Travis and CircleCI)

This reporter comes with a codechecks CI integration that displays a pull request's gas consumption changes relative to its target branch in the Github UI. It's like coveralls for gas. The codechecks service is free for open source and maintained by MakerDao engineer @krzkaczor.

Complete set-up guide here (it's easy).

Screen Shot 2019-06-18 at 12 25 49 PM


⚠️ 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.

Option Type Default Description
currency String 'EUR' National currency to represent gas costs in. Exchange rates loaded at runtime from the coinmarketcap api. Available currency codes can be found here.
coinmarketcap String (unprotected API key) API key to use when fetching current market price data. (Use this if you stop seeing price data)
gasPrice Number (varies) Denominated in gwei. Default is loaded at runtime from the eth gas station api
outputFile String stdout File path to write report output to
noColors Boolean false Suppress report color. Useful if you are printing to file b/c terminal colorization corrupts the text.
onlyCalledMethods Boolean true Omit methods that are never called from report.
rst Boolean false Output with a reStructured text code-block directive. Useful if you want to include report in RTD
rstTitle String "" Title for reStructured text header (See Travis for example output)
showTimeSpent Boolean false Show the amount of time spent as well as the gas consumed
excludeContracts String[] [] Contract names to exclude from report. Ex: ['Migrations']
src String "contracts" Folder in root directory to begin search for .sol files. This can also be a path to a subfolder relative to the root, e.g. "planets/annares/contracts"
url String RPC client url (ex: "http://localhost:8545")
proxyResolver Function none Custom method to resolve identity of methods managed by a proxy contract.
artifactType Function or String "truffle-v5" Compilation artifact format to consume. (See advanced use.)
showMethodSig Boolean false Display complete method signatures. Useful when you have overloaded methods you can't tell apart.
maxMethodDiff Number undefined Codechecks failure threshold, triggered when the % diff for any method is greater than number (integer)
maxDeploymentDiff Number undefined Codechecks failure threshold, triggered when the % diff for any deployment is greater than number (integer)

Advanced Use

An advanced use guide is available here. Topics include:

  • Getting accurate gas data when using proxy contracts like EtherRouter or ZeppelinOS.
  • Configuring the reporter to work with non-truffle, non-buidler projects.

Example Reports

Usage Notes

  • Requires Node >= 8.
  • You cannot use ganache-core as an in-process provider for your test suite. The reporter makes sync RPC calls while collecting data and your tests will hang unless the client is launched as a separate process.
  • Method calls that throw are filtered from the stats.
  • Contracts that are only ever created by other contracts within Solidity are not shown in the deployments table.


Feel free to open PRs or issues. There is an integration test and one of the mock test cases is expected to fail. If you're adding an option, you can vaildate it in CI by adding it to the mock options config located here.


All the ideas in this utility have been borrowed from elsewhere. Many thanks to:

  • @maurelian - Mocha reporting gas instead of time is his idea.
  • @cag - The table borrows from / is based his gas statistics work for the Gnosis contracts.
  • Neufund - Block limit size ratios for contract deployments and euro pricing are borrowed from their ico-contracts test suite.