task.js

const istanbul = require('istanbul-lib-coverage')
const { join } = require('path')
const { existsSync, mkdirSync, readFileSync, writeFileSync } = require('fs')
const execa = require('execa')
const fs = require('fs')
const { fixSourcePathes } = require('./utils')

const debug = require('debug')('code-coverage')

// these are standard folder and file names used by NYC tools
const processWorkingDirectory = process.cwd()
const outputFolder = '.nyc_output'
const coverageFolder = join(processWorkingDirectory, outputFolder)
const nycFilename = join(coverageFolder, 'out.json')

// there might be custom "nyc" options in the user package.json
// see https://github.com/istanbuljs/nyc#configuring-nyc
// potentially there might be "nyc" options in other configuration files
// it allows, but for now ignore those options
const pkgFilename = join(processWorkingDirectory, 'package.json')
const pkg = fs.existsSync(pkgFilename)
  ? JSON.parse(fs.readFileSync(pkgFilename, 'utf8'))
  : {}
const nycOptions = pkg.nyc || {}

function saveCoverage(coverage) {
  if (!existsSync(coverageFolder)) {
    mkdirSync(coverageFolder)
    debug('created folder %s for output coverage', coverageFolder)
  }

  writeFileSync(nycFilename, JSON.stringify(coverage, null, 2))
}

module.exports = {
  /**
   * Clears accumulated code coverage information.
   *
   * Interactive mode with "cypress open"
   *    - running a single spec or "Run all specs" needs to reset coverage
   * Headless mode with "cypress run"
   *    - runs EACH spec separately, so we cannot reset the coverage
   *      or we will lose the coverage from previous specs.
   */
  resetCoverage({ isInteractive }) {
    if (isInteractive) {
      debug('reset code coverage in interactive mode')
      const coverageMap = istanbul.createCoverageMap({})
      saveCoverage(coverageMap)
    }
    /*
        Else:
          in headless mode, assume the coverage file was deleted
          before the `cypress run` command was called
          example: rm -rf .nyc_output || true
      */

    return null
  },

  /**
   * Combines coverage information from single test
   * with previously collected coverage.
   */
  combineCoverage(coverage) {
    fixSourcePathes(coverage)
    const previous = existsSync(nycFilename)
      ? JSON.parse(readFileSync(nycFilename))
      : istanbul.createCoverageMap({})
    const coverageMap = istanbul.createCoverageMap(previous)
    coverageMap.merge(coverage)
    saveCoverage(coverageMap)
    debug('wrote coverage file %s', nycFilename)

    return null
  },

  /**
   * Saves coverage information as a JSON file and calls
   * NPM script to generate HTML report
   */
  coverageReport() {
    if (!existsSync(nycFilename)) {
      console.warn('Cannot find coverage file %s', nycFilename)
      console.warn('Skipping coverage report')
      return null
    }

    const reportDir = nycOptions['report-dir'] || './coverage'
    const reporter = nycOptions['reporter'] || ['lcov', 'clover', 'json']
    const reporters = Array.isArray(reporter)
      ? reporter.map(name => `--reporter=${name}`)
      : `--reporter=${reporter}`

    // should we generate report via NYC module API?
    const command = 'nyc'
    const args = [
      'report',
      '--report-dir',
      reportDir,
      '--temp-dir',
      coverageFolder
    ].concat(reporters)
    debug(
      'saving coverage report using command: "%s %s"',
      command,
      args.join(' ')
    )
    debug('current working directory is %s', process.cwd())
    return execa(command, args, { stdio: 'inherit' })
  }
}