# solidity-coverage
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### Code coverage for Solidity testing
![coverage example](https://cdn-images-1.medium.com/max/800/1*uum8t-31bUaa6dTRVVhj6w.png)

For more details about what this is, how it works and potential limitations, see 
[the accompanying article](https://blog.colony.io/code-coverage-for-solidity-eecfa88668c2).

**solidity-coverage** is a stand-alone fork of [Solcover](https://github.com/JoinColony/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](https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/truffle.js) 
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**
```javascript
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](https://github.com/sc-forks/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**
```javascript
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](https://github.com/trufflesuite/truffle/issues/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](https://github.com/trufflesuite/truffle/issues/348).
HDWalletProvider tends to crash solidity-coverage and you should make sure its constructor isn't invoked while 
coverage is running. An example workaround can be found at the zeppelin-solidity project 
[here](https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/truffle.js#L8-L10), where a 
coverage script sets a shell environment variable and `truffle.js` checks 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](https://github.com/sc-forks/solidity-coverage/issues). 

+ **metacoin**: The default truffle project
  + [HTML reports](https://sc-forks.github.io/metacoin/)
  + [Metacoin with solidity-coverage installed](https://github.com/sc-forks/metacoin) (simple, without configuration)
+ **zeppelin-solidity** at commit 453a19825013a586751b87c67bebd551a252fb50
  + [HTML reports]( https://sc-forks.github.io/zeppelin-solidity/)
  + [Zeppelin with solidity-coverage installed](https://github.com/sc-forks/zeppelin-solidity) (declares own coverage network in truffle.js)
+ **numeraire** at commit 5ac3fa432c6b4192468c95a66e52ca086c804c95
  + [HTML reports](https://sc-forks.github.io/contract/)
  + [Numeraire with solidity-coverage installed](https://github.com/sc-forks/contract) (uses .solcover.js)

### Contribution Guidelines

Contributions are welcome! If you're opening a PR that adds features please consider writing some
[unit tests](https://github.com/sc-forks/solidity-coverage/tree/master/test) for them. You could 
also lint your submission with `npm run lint`. Bugs can be reported in the 
[issues](https://github.com/sc-forks/solidity-coverage/issues).  

### Contributors
+ [@area](https://github.com/area)
+ [@cgewecke](https://github.com/cgewecke)
+ [@adriamb](https://github.com/adriamb)