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)
• testrpcOptions: { String } options to append to a command line invocation of testrpc.
  • ex: --secure --unlock "0x1234..." --unlock "0xabcd...".
  • NB: if you specify the port in your rpc options string, also declare it as a 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 a contracts folder in your root directory. dir allows you to define a relative path from the root directory to the contracts folder. dir: "./secretDirectory" would tell solidity-coverage to look for ./secretDirectory/contracts

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.

Events testing: Because solidity-coverage injects events into your contracts to log which lines your tests reach, any tests that ask how many events are fired or where the event sits in the logs array will probably error while coverage is being generated.

Using require in migrations.js files: Truffle overloads Node's require function but implements a simplified search algorithm for node_modules packages (see Truffle issue #383). Because solidity-coverage copies an instrumented version of your project into a temporary folder, require statements handled by Truffle internally won't resolve correctly.

Using HDWalletProvider in truffle.js: See Truffle issue #348. HDWalletProvider crashes solidity-coverage, so its constructor shouldn't be invoked when generating coverage. An example workaround can be found at the zeppelin-solidity project here, which uses a shell script to set environment variable and has truffle.js check it before instantiating the wallet.

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 453a19825013a586751b87c67bebd551a252fb50
  • HTML reports
  • Zeppelin with solidity-coverage installed (declares own coverage network in truffle.js)
• numeraire at commit 5ac3fa432c6b4192468c95a66e52ca086c804c95
  • HTML reports
  • Numeraire with solidity-coverage installed (uses .solcover.js)

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.

Contributors

• @area
• @cgewecke
• @adriamb