feat: implement Istanbul reporting

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 node_modules
 .nyc_output
+coverage

README.md

@@ -3,7 +3,7 @@
 Code-coverage using [v8's Inspector](https://nodejs.org/dist/latest-v8.x/docs/api/inspector.html)
 that's compatible with [Istanbul's reporters](https://istanbul.js.org/docs/advanced/alternative-reporters/).
 
-Like [nyc](https://github.com/istanbuljs/nyc), c8 just magically works, simply:
+Like [nyc](https://github.com/istanbuljs/nyc), c8 just magically works:
 
 ```bash
 npm i c8 -g
@@ -12,12 +12,12 @@ c8 node foo.js
 
 The above example will collect coverage for `foo.js` using v8's inspector.
 
-TODO:
+## remaining work
 
 - [x] write logic for converting v8 coverage output to [Istanbul Coverage.json format](https://github.com/gotwarlost/istanbul/blob/master/coverage.json.md).
   * https://github.com/bcoe/v8-to-istanbul
 
-- [ ] talk to Node.js project about silencing messages:
+- [ ] talk to node.js project about silencing messages:
 
    > `Debugger listening on ws://127.0.0.1:56399/e850110a-c5df-41d8-8ef2-400f6829617f`.
 
@@ -29,5 +29,5 @@ TODO:
 - [x] process.exit() can't perform an async operation; how can we track coverage
   for scripts that exit?
   * we can now listen for the `Runtime.executionContextDestroyed` event.
-- [ ] figure out why instrumentation of .mjs files does not work:
-  * see: https://github.com/nodejs/node/issues/17336
+- [x] figure out why instrumentation of .mjs files does not work:
+  * see: https://github.com/nodejs/node/issues/17336

bin/c8.js

@@ -1,15 +1,36 @@
 #!/usr/bin/env node
 'use strict'
 
-const {isAbsolute} = require('path')
-const argv = require('yargs').parse()
 const CRI = require('chrome-remote-interface')
+const Exclude = require('test-exclude')
+const {isAbsolute} = require('path')
+const mkdirp = require('mkdirp')
+const report = require('../lib/report')
+const {resolve} = require('path')
+const rimraf = require('rimraf')
 const spawn = require('../lib/spawn')
+const uuid = require('uuid')
+const v8ToIstanbul = require('v8-to-istanbul')
+const {writeFileSync} = require('fs')
+const {
+  hideInstrumenteeArgs,
+  hideInstrumenterArgs,
+  yargs
+} = require('../lib/parse-args')
+
+const instrumenterArgs = hideInstrumenteeArgs()
+const argv = yargs.parse(instrumenterArgs)
 
-;(async () => {
+const exclude = Exclude({
+  include: argv.include,
+  exclude: argv.exclude
+})
+
+;(async function executeWithCoverage (instrumenteeArgv) {
   try {
-    const info = await spawn(process.execPath,
-                             [`--inspect-brk=0`].concat(process.argv.slice(2)))                      
+    const bin = instrumenteeArgv.shift()
+    const info = await spawn(bin,
+                             [`--inspect-brk=0`].concat(instrumenteeArgv))
     const client = await CRI({port: info.port})
 
     const initialPause = new Promise((resolve) => {
@@ -42,24 +63,40 @@ const spawn = require('../lib/spawn')
     await Debugger.resume()
 
     await executionComplete
-    await outputCoverage(Profiler)
-    client.close()
-
+    const allV8Coverage = await collectV8Coverage(Profiler)
+    writeIstanbulFormatCoverage(allV8Coverage)
+    await client.close()
+    report({
+      reporter: Array.isArray(argv.reporter) ? argv.reporter : [argv.reporter],
+      coverageDirectory: argv.coverageDirectory,
+      watermarks: argv.watermarks
+    })
   } catch (err) {
     console.error(err)
     process.exit(1)
   }
-})()
+})(hideInstrumenterArgs(argv))
 
-async function outputCoverage (Profiler) {
-  const IGNORED_PATHS = [
-    /\/bin\/wrap.js/,
-    /\/node_modules\//,
-    /node-spawn-wrap/
-  ]
+async function collectV8Coverage (Profiler) {
   let {result} = await Profiler.takePreciseCoverage()
   result = result.filter(({url}) => {
-    return isAbsolute(url) && IGNORED_PATHS.every(ignored => !ignored.test(url))
+    url = url.replace('file://', '')
+    return isAbsolute(url) && exclude.shouldInstrument(url)
+  })
+  return result
+}
+
+function writeIstanbulFormatCoverage (allV8Coverage) {
+  const tmpDirctory = resolve(argv.coverageDirectory, './tmp')
+  rimraf.sync(tmpDirctory)
+  mkdirp.sync(tmpDirctory)
+  allV8Coverage.forEach((v8) => {
+    const script = v8ToIstanbul(v8.url)
+    script.applyCoverage(v8.functions)
+    writeFileSync(
+      resolve(tmpDirctory, `./${uuid.v4()}.json`),
+      JSON.stringify(script.toIstanbul(), null, 2),
+      'utf8'
+    )
   })
-  console.log(JSON.stringify(result, null, 2))
 }

lib/parse-args.js

@@ -0,0 +1,63 @@
+const Exclude = require('test-exclude')
+const findUp = require('find-up')
+const {readFileSync} = require('fs')
+const yargs = require('yargs')
+const parser = require('yargs-parser')
+
+const configPath = findUp.sync(['.c8rc', '.c8rc.json'])
+const config = configPath ? JSON.parse(readFileSync(configPath)) : {}
+
+yargs
+  .usage('$0 [opts] [script] [opts]')
+  .option('reporter', {
+    alias: 'r',
+    describe: 'coverage reporter(s) to use',
+    default: 'text'
+  })
+  .option('exclude', {
+    alias: 'x',
+    default: Exclude.defaultExclude,
+    describe: 'a list of specific files and directories that should be excluded from coverage, glob patterns are supported.'
+  })
+  .option('include', {
+    alias: 'n',
+    default: [],
+    describe: 'a list of specific files that should be covered, glob patterns are supported'
+  })
+  .option('coverage-directory', {
+    default: './coverage',
+    describe: 'directory to output coverage JSON and reports'
+  })
+  .pkgConf('c8')
+  .config(config)
+  .demandCommand(1)
+  .epilog('visit https://git.io/vHysA for list of available reporters')
+
+function hideInstrumenterArgs (yargv) {
+  var argv = process.argv.slice(1)
+  argv = argv.slice(argv.indexOf(yargv._[0]))
+  if (argv[0][0] === '-') {
+    argv.unshift(process.execPath)
+  }
+  return argv
+}
+
+function hideInstrumenteeArgs () {
+  let argv = process.argv.slice(2)
+  const yargv = parser(argv)
+
+  if (!yargv._.length) return argv
+
+  // drop all the arguments after the bin being
+  // instrumented by c8.
+  argv = argv.slice(0, argv.indexOf(yargv._[0]))
+  argv.push(yargv._[0])
+
+  return argv
+}
+
+module.exports = {
+  yargs,
+  hideInstrumenterArgs,
+  hideInstrumenteeArgs
+}

lib/report.js

@@ -0,0 +1,51 @@
+const libCoverage = require('istanbul-lib-coverage')
+const libReport = require('istanbul-lib-report')
+const reports = require('istanbul-reports')
+const {readdirSync, readFileSync} = require('fs')
+const {resolve} = require('path')
+
+class Report {
+  constructor ({reporter, coverageDirectory, watermarks}) {
+    this.reporter = reporter
+    this.coverageDirectory = coverageDirectory
+    this.watermarks = watermarks
+  }
+  run () {
+    const map = this._getCoverageMapFromAllCoverageFiles()
+    var context = libReport.createContext({
+      dir: './coverage',
+      watermarks: this.watermarks
+    })
+
+    const tree = libReport.summarizers.pkg(map)
+
+    this.reporter.forEach(function (_reporter) {
+      tree.visit(reports.create(_reporter), context)
+    })
+  }
+  _getCoverageMapFromAllCoverageFiles () {
+    const map = libCoverage.createCoverageMap({})
+
+    this._loadReports().forEach(function (report) {
+      map.merge(report)
+    })
+
+    return map
+  }
+  _loadReports () {
+    const tmpDirctory = resolve(this.coverageDirectory, './tmp')
+    const files = readdirSync(tmpDirctory)
+
+    return files.map((f) => {
+      return JSON.parse(readFileSync(
+        resolve(tmpDirctory, f),
+        'utf8'
+      ))
+    })
+  }
+}
+
+module.exports = function (opts) {
+  const report = new Report(opts)
+  report.run()
+}

lib/spawn.js

@@ -2,7 +2,7 @@ const {spawn} = require('child_process')
 
 const debuggerRe = /Debugger listening on ws:\/\/[^:]*:([^/]*)/
 
-module.exports = function (execPath, args=[]) {
+module.exports = function (execPath, args = []) {
   const info = {
     port: -1
   }
@@ -11,7 +11,7 @@ module.exports = function (execPath, args=[]) {
       stdio: [process.stdin, process.stdout, 'pipe'],
       env: process.env,
       cwd: process.cwd()
-    });
+    })
 
     proc.stderr.on('data', (outBuffer) => {
       const outString = outBuffer.toString('utf8')
@@ -23,11 +23,13 @@ module.exports = function (execPath, args=[]) {
         console.error(outString)
       }
     })
-    
+
     proc.on('close', (code) => {
       if (info.port === -1) {
         return reject(Error('could not connect to inspector'))
+      } else {
+        process.exitCode = code
       }
     })
   })
-}
+}