solidity-coverage

Code coverage for Solidity testing

For more details about what this is, how it works and potential limitations, see the accompanying article.

solidity-coverage is a stand-alone fork of Solcover

Install

$ npm install --save-dev solidity-coverage

Run

$ ./node_modules/.bin/solidity-coverage

Tests run signficantly slower while coverage is being generated. A 1 to 2 minute delay between the end of Truffle compilation and the beginning of test execution is possible if your test suite is large. Large solidity files can also take a while to instrument.

Configuration

By default, solidity-coverage generates a stub truffle.js that accomodates its special gas needs and connects to a modified version of testrpc on port 8555. If your tests will run on the development network using a standard truffle.js and a testrpc instance with no special options, you shouldn't have to do any configuration. If your tests depend on logic added to truffle.js - for example: zeppelin-solidity uses the file to expose a babel polyfill that its suite requires - you can override the default behavior by declaring a coverage network in truffle.js. solidity-coverage will use your 'truffle.js' instead of a dynamically generated one.

Example coverage network config

module.exports = {
  networks: {
    development: {
      host: "localhost",
      port: 8545,
      network_id: "*" // Match any network id
    },
    coverage: {
      host: "localhost",
      network_id: "*",
      port: 8555,         // <-- Use port 8555  
      gas: 0xfffffffffff, // <-- Use this high gas value
      gasPrice: 0x01      // <-- Use this low gas price
    }
  }
};

You can also create a .solcover.js config file in the root directory of your project and specify some additional options:

port: { Number } Port to run testrpc on / have truffle connect to. (Default: 8555)
accounts: { Number } Number of accounts to launch testrpc with. (Default: 35)
testrpcOptions: { String } options to append to a command line invocation of testrpc.
- ex: --secure --port 8555 --unlock "0x1234..." --unlock "0xabcd...".
- NB: you should specify a port in your rpc options string and also declare it in the config's port option.
testCommand: { String } By default solidity-coverage runs truffle test. This option lets you run an arbitrary test command instead, like: mocha --timeout 5000.
- remember to set the config's port option to whatever port your tests use (probably 8545).
- make sure you don't have another instance of testrpc running on that port (web3 will error if you do).
norpc: { Boolean } When true, solidity-coverage will not launch its own testrpc instance. This can be useful if you are using a different vm like the sc-forks version of pyethereum.
dir: { String } : Solidity-coverage usually looks for contracts and test folders in your root directory. dir allows you to define a relative path from the root directory to those assets. dir: "./<dirname>" would tell solidity-coverage to look for ./<dirname>/contracts/ and ./<dirname>/test/
copyNodeModules: { Boolean } : When true, will copy node_modules into the coverage environment. False by default, and may significantly increase the time for coverage to complete if enabled. Only enable if required.
skipFiles: { Array } : An array of contracts (with paths expressed relative to the contracts directory) that should be skipped when doing instrumentation. Migrations.sol is skipped by default, and does not need to be added to this configuration option if it is used.

Example .solcover.js config file

module.exports = {
    port: 6545,
    testrpcOptions: '-p 6545 -u 0x54fd80d6ae7584d8e9a19fe1df43f04e5282cc43',
    testCommand: 'mocha --timeout 5000',
    norpc: true,
    dir: './secretDirectory'
};

Known Issues

Hardcoded gas costs: If you have hardcoded gas costs into your tests some of them may fail when using solidity-coverage. This is because the instrumentation process increases the gas costs for using the contracts, due to the extra events. If this is the case, then the coverage may be incomplete. To avoid this, using estimateGas to estimate your gas costs should be more resilient in most cases.

Example (in a Truffle test):

// Hardcoded Gas Call
MyContract.deployed().then(instance => {       
  instance.claimTokens(0, {gasLimit: 3000000}).then(() => {
      assert(web3.eth.getBalance(instance.address).equals(new BigNumber('0')))
      done();
  })
});

// Using gas estimation
MyContract.deployed().then(instance => {       
  const data = instance.contract.claimTokens.getData(0);
  const gasEstimate = web3.eth.estimateGas({to: instance.address, data: data});
  instance.claimTokens(0, {gasLimit: gasEstimate}).then(() => {
      assert(web3.eth.getBalance(instance.address).equals(new BigNumber('0')))
      done();
  })
});

Using HDWalletProvider in truffle.js: See Truffle issue #348. HDWalletProvider crashes solidity-coverage, so its constructor shouldn't be invoked while running this tool. A workaround can be found at the zeppelin-solidity project here, where a shell script is used to set an environment variable which truffle.js checks before instantiating the wallet.

Running out of memory: (See issue #59). If your target contains dozens of contracts, you may run up against node's 1.7MB memory cap during the contract compilation step. This can be addressed by setting the testCommand option in .solcover.js as below (note the path - it reaches outside a temporarily generated coverageEnv folder to access a locally installed version of truffle in your root directory's node_modules):

testCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle test --network coverage'

Large projects may also hit their CI container memcap running coverage after unit tests. This can be addressed on TravisCI by adding sudo: required to the travis.yml, which raises the container's limit to 7.5MB (ProTip courtesy of @federicobond.

Examples

WARNING: This utility is in development and its accuracy is unknown. If you find discrepancies between the coverage report and your suite's behavior, please open an issue.

metacoin: The default truffle project
- HTML reports
- Metacoin with solidity-coverage installed (simple, without configuration)
zeppelin-solidity at commit 453a198
- HTML reports(declares own coverage network in truffle.js)
- Zeppelin with solidity-coverage installed
numeraire at commit 695b0a0(uses .solcover.js)
- HTML reports
- Numeraire with solidity-coverage installed

Contribution Guidelines

Contributions are welcome! If you're opening a PR that adds features please consider writing some unit tests for them. You could also lint your submission with npm run lint. Bugs can be reported in the issues.

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