Istanbul (ES6+ ready using Babel recently) tasks for Start.

npm install --save-dev start-istanbul
# or
yarn add --dev start-istanbul

The sequence of tasks is simple: "instrument" sources, run tests, report collected code coverage and then check the result against provided thresholds (optional).

import Start from 'start';
import reporter from 'start-pretty-reporter';
import files from 'start-files';
import clean from 'start-clean';
import * as istanbul from 'start-istanbul';
import mocha from 'start-mocha';
const start = Start(reporter());
export const coverage = () => start(
  files('coverage/'),
  clean(),
  files('lib/**/*.js'),
  istanbul.instrument({ esModules: true }),
  files('test/**/*.js'),
  mocha(),
  istanbul.report([ 'lcovonly', 'html', 'text-summary' ]),
  istanbul.thresholds({ functions: 100 })
);

Instrument task relies on array of files, see documentation for details.

istanbul.instrument(options)

• options – Istanbul instrumenter options (note that you can't change coverageVariable at this moment)

istanbul.report(formats)

• formats – Istanbul reporter formats, [ 'lcovonly', 'text-summary' ] by default

istanbul.thresholds(thresholds)

• thresholds – { lines, statements, functions, branches } object, {} by default

It works as 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.

Only defined keys will be processed, for example:

{
  statements: 100,
  functions: -10
}