index.js

'use strict';

const { Session } = require('inspector');
const { promisify } = require('util');

class CoverageInstrumenter {
  constructor() {
    this.session = new Session();

    this.postSession = promisify(this.session.post.bind(this.session));
  }

  async startInstrumenting() {
    this.session.connect();

    await this.postSession('Profiler.enable');

    await this.postSession('Profiler.startPreciseCoverage', {
      callCount: true,
      detailed: true,
    });
  }

  async stopInstrumenting() {
    const {result} = await this.postSession(
      'Profiler.takePreciseCoverage',
    );

    await this.postSession('Profiler.stopPreciseCoverage');

    await this.postSession('Profiler.disable');

    return result;
  }
}

module.exports.CoverageInstrumenter = CoverageInstrumenter;