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gotwarlost / istanbul

Yet another JS code coverage tool that computes statement, line, function and branch coverage with module loader hooks to transparently add coverage when running tests. Supports all JS coverage use cases including unit tests, server side functional tests and browser tests. Built for scale.
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Istanbul - a JS code coverage tool written in JS

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NPM

Deprecation Notice: this version of istanbul is deprecated, we will not be landing pull requests or releasing new versions. But don't worry, the Istanbul 2.0 API is now available and is being actively developed in the new istanbuljs organization.

New v0.4.0 now has beautiful HTML reports. Props to Tom MacWright @tmcw for a fantastic job!

Features

Use cases

Supports the following use cases and more

Getting started

$ npm install -g istanbul

The best way to see it in action is to run node unit tests. Say you have a test script test.js that runs all tests for your node project without coverage.

Simply:

$ cd /path/to/your/source/root
$ istanbul cover test.js

and this should produce a coverage.json, lcov.info and lcov-report/*html under ./coverage

Sample of code coverage reports produced by this tool (for this tool!):

HTML reports

Usage on Windows

Istanbul assumes that the command passed to it is a JS file (e.g. Jasmine, vows etc.), this is however not true on Windows where npm wrap bin files in a .cmd file. Since Istanbul can not parse .cmd files you need to reference the bin file manually.

Here is an example using Jasmine 2:

istanbul cover node_modules\jasmine\bin\jasmine.js

In order to use this cross platform (e.i. Linux, Mac and Windows), you can insert the above line into the script object in your package.json file but with normal slash.

"scripts": {
    "test": "istanbul cover node_modules/jasmine/bin/jasmine.js"
}

Configuring

Drop a .istanbul.yml file at the top of the source tree to configure istanbul. istanbul help config tells you more about the config file format.

The command line

$ istanbul help

gives you detailed help on all commands.

Usage: istanbul help config | <command>

`config` provides help with istanbul configuration

Available commands are:

      check-coverage
              checks overall/per-file coverage against thresholds from coverage
              JSON files. Exits 1 if thresholds are not met, 0 otherwise

      cover   transparently adds coverage information to a node command. Saves
              coverage.json and reports at the end of execution

      help    shows help

      instrument
              instruments a file or a directory tree and writes the
              instrumented code to the desired output location

      report  writes reports for coverage JSON objects produced in a previous
              run

      test    cover a node command only when npm_config_coverage is set. Use in
              an `npm test` script for conditional coverage

Command names can be abbreviated as long as the abbreviation is unambiguous

To get detailed help for a command and what command-line options it supports, run:

istanbul help <command>

(Most of the command line options are not covered in this document.)

The cover command

$ istanbul cover my-test-script.js -- my test args
# note the -- between the command name and the arguments to be passed

The cover command can be used to get a coverage object and reports for any arbitrary node script. By default, coverage information is written under ./coverage - this can be changed using command-line options.

The cover command can also be passed an optional --handle-sigint flag to enable writing reports when a user triggers a manual SIGINT of the process that is being covered. This can be useful when you are generating coverage for a long lived process.

The test command

The test command has almost the same behavior as the cover command, except that it skips coverage unless the npm_config_coverage environment variable is set.

This command is deprecated since the latest versions of npm do not seem to set the npm_config_coverage variable.

The instrument command

Instruments a single JS file or an entire directory tree and produces an output directory tree with instrumented code. This should not be required for running node unit tests but is useful for tests to be run on the browser.

The report command

Writes reports using coverage*.json files as the source of coverage information. Reports are available in multiple formats and can be individually configured using the istanbul config file. See istanbul help report for more details.

The check-coverage command

Checks the coverage of statements, functions, branches, and lines against the provided thresholds. Positive thresholds are taken to be the minimum percentage required and negative numbers are taken to be the number of uncovered entities allowed.

Ignoring code for coverage

See ignoring-code-for-coverage.md for the spec.

API

All the features of istanbul can be accessed as a library.

Instrument code

    var istanbul = require('istanbul');
    var instrumenter = new istanbul.Instrumenter();

    var generatedCode = instrumenter.instrumentSync('function meaningOfLife() { return 42; }',
        'filename.js');

Generate reports given a bunch of coverage JSON objects

    var istanbul = require('istanbul'),
        collector = new istanbul.Collector(),
        reporter = new istanbul.Reporter(),
        sync = false;

    collector.add(obj1);
    collector.add(obj2); //etc.

    reporter.add('text');
    reporter.addAll([ 'lcov', 'clover' ]);
    reporter.write(collector, sync, function () {
        console.log('All reports generated');
    });

For the gory details consult the public API

Multiple Process Usage

Istanbul can be used in a multiple process environment by running each process with Istanbul, writing a unique coverage file for each process, and combining the results when generating reports. The method used to perform this will depend on the process forking API used. For example when using the cluster module you must setup the master to start child processes with Istanbul coverage, disable reporting, and output coverage files that include the PID in the filename. Before each run you may need to clear out the coverage data directory.

    if(cluster.isMaster) {
        // setup cluster if running with istanbul coverage
        if(process.env.running_under_istanbul) {
            // use coverage for forked process
            // disabled reporting and output for child process
            // enable pid in child process coverage filename
            cluster.setupMaster({
                exec: './node_modules/.bin/istanbul',
                args: [
                    'cover', '--report', 'none', '--print', 'none', '--include-pid',
                    process.argv[1], '--'].concat(process.argv.slice(2))
            });
        }
        // ...
        // ... cluster.fork();
        // ...
    } else {
        // ... worker code
    }

Coverage.json

For details on the format of the coverage.json object, see here.

License

istanbul is licensed under the BSD License.

Third-party libraries

The following third-party libraries are used by this module:

Inspired by

Shout out to

Why the funky name?

Since all the good ones are taken. Comes from the loose association of ideas across coverage, carpet-area coverage, the country that makes good carpets and so on...