feat: switch to using Node's built in coverage

README.md

@@ -1,6 +1,6 @@
-# c8 - native v8 code-coverage
+# c8 - native V8 code-coverage
 
-Code-coverage using [v8's Inspector](https://nodejs.org/dist/latest-v8.x/docs/api/inspector.html)
+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:
@@ -10,20 +10,10 @@ npm i c8 -g
 c8 node foo.js
 ```
 
-The above example will collect coverage for `foo.js` using v8's inspector.
+The above example will collect coverage for `foo.js` using V8's inspector.
 
 ## Disclaimer
 
-c8 uses bleeding edge v8 features (_it's an ongoing experiment, testing
-what will eventually be possible in the realm of test coverage in Node.js_).
-
-For the best experience, try running with [a canary build of Node.js](https://github.com/v8/node).
-
-## How it Works
-
-Before running your application c8 creates [an inspector session](https://nodejs.org/api/inspector.html) in v8 and enables v8's
-[built in coverage reporting](https://v8project.blogspot.com/2017/12/javascript-code-coverage.html).
-
-Just before your application exits, c8 fetches the coverage information from
-v8 and writes it to disk in a format compatible with
-[Istanbul's reporters](https://istanbul.js.org/).
+c8 uses
+[bleeding edge Node.js features](https://github.com/nodejs/node/pull/22527),
+make sure you're running Node.js `>= 10.10.0`.

bin/c8.js

@@ -4,31 +4,28 @@
 const foreground = require('foreground-child')
 const mkdirp = require('mkdirp')
 const report = require('../lib/report')
-const {resolve} = require('path')
+const { resolve } = require('path')
 const rimraf = require('rimraf')
-const sw = require('spawn-wrap')
 const {
   hideInstrumenteeArgs,
   hideInstrumenterArgs,
   yargs
 } = require('../lib/parse-args')
-
 const instrumenterArgs = hideInstrumenteeArgs()
-
 const argv = yargs.parse(instrumenterArgs)
-
 const tmpDirctory = resolve(argv.coverageDirectory, './tmp')
 rimraf.sync(tmpDirctory)
 mkdirp.sync(tmpDirctory)
 
-sw([require.resolve('../lib/wrap')], {
-  C8_ARGV: JSON.stringify(argv)
-})
+process.env.NODE_V8_COVERAGE = tmpDirctory
 
 foreground(hideInstrumenterArgs(argv), (out) => {
   report({
+    include: argv.include,
+    exclude: argv.exclude,
     reporter: Array.isArray(argv.reporter) ? argv.reporter : [argv.reporter],
     coverageDirectory: argv.coverageDirectory,
-    watermarks: argv.watermarks
+    watermarks: argv.watermarks,
+    resolve: argv.resolve
   })
 })

lib/parse-args.js

@@ -1,6 +1,6 @@
 const Exclude = require('test-exclude')
 const findUp = require('find-up')
-const {readFileSync} = require('fs')
+const { readFileSync } = require('fs')
 const yargs = require('yargs')
 const parser = require('yargs-parser')
 
@@ -28,6 +28,10 @@ yargs
     default: './coverage',
     describe: 'directory to output coverage JSON and reports'
   })
+  .option('resolve', {
+    default: '',
+    describe: 'resolve paths to alternate base directory'
+  })
   .pkgConf('c8')
   .config(config)
   .demandCommand(1)

lib/report.js

@@ -1,14 +1,29 @@
+const Exclude = require('test-exclude')
 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')
+const { readdirSync, readFileSync } = require('fs')
+const { resolve } = require('path')
+const v8CoverageMerge = require('v8-coverage-merge')
+const v8toIstanbul = require('v8-to-istanbul')
 
 class Report {
-  constructor ({reporter, coverageDirectory, watermarks}) {
+  constructor ({
+    exclude,
+    include,
+    reporter,
+    coverageDirectory,
+    watermarks,
+    resolve
+  }) {
     this.reporter = reporter
     this.coverageDirectory = coverageDirectory
     this.watermarks = watermarks
+    this.resolve = resolve
+    this.exclude = Exclude({
+      exclude: exclude,
+      include: include
+    })
   }
   run () {
     const map = this._getCoverageMapFromAllCoverageFiles()
@@ -25,9 +40,34 @@ class Report {
   }
   _getCoverageMapFromAllCoverageFiles () {
     const map = libCoverage.createCoverageMap({})
+    const mergedResults = {}
+    this._loadReports().forEach((report) => {
+      report.result.forEach((result) => {
+        if (this.exclude.shouldInstrument(result.url)) {
+          if (mergedResults[result.url]) {
+            mergedResults[result.url] = v8CoverageMerge(
+              mergedResults[result.url],
+              result
+            )
+          } else {
+            mergedResults[result.url] = result
+          }
+        }
+      })
+    })
 
-    this._loadReports().forEach(function (report) {
-      map.merge(report)
+    Object.keys(mergedResults).forEach((url) => {
+      const result = mergedResults[url]
+      // console.info(JSON.stringify(result, null, 2))
+      try {
+        const path = resolve(this.resolve, result.url)
+        const script = v8toIstanbul(path)
+        script.applyCoverage(result.functions)
+        map.merge(script.toIstanbul())
+      } catch (err) {
+        // most likely this was an internal Node.js library.
+        if (err.code !== 'ENOENT' && err.code !== 'EISDIR') throw err
+      }
     })
 
     return map

package.json

@@ -5,16 +5,10 @@
   "main": "index.js",
   "bin": "./bin/c8.js",
   "scripts": {
-    "bundle": "bundle-dependencies update",
-    "test": "nyc mocha ./test/*.js",
+    "test": "./bin/c8.js --reporter=html --reporter=text mocha ./test/*.js",
     "posttest": "standard",
     "release": "standard-version"
   },
-  "c8": {
-    "exclude": [
-      "test/*.js"
-    ]
-  },
   "standard": {
     "ignore": [
       "test/fixtures"
@@ -28,49 +22,35 @@
     "profiler",
     "inspector"
   ],
-  "engines": {
-    "node": ">=8.8.1"
-  },
   "author": "Ben Coe <ben@npmjs.com>",
   "license": "ISC",
   "dependencies": {
-    "find-up": "^2.1.0",
+    "find-up": "^3.0.0",
     "foreground-child": "^1.5.6",
-    "istanbul-lib-coverage": "^1.1.1",
-    "istanbul-lib-report": "^1.1.2",
-    "istanbul-reports": "^1.1.3",
+    "istanbul-lib-coverage": "^2.0.1",
+    "istanbul-lib-report": "^2.0.1",
+    "istanbul-reports": "^2.0.0",
     "mkdirp": "^0.5.1",
     "rimraf": "^2.6.2",
-    "signal-exit": "^3.0.2",
-    "spawn-wrap": "^1.4.2",
-    "test-exclude": "^4.1.1",
-    "uuid": "^3.1.0",
+    "test-exclude": "^5.0.0",
+    "uuid": "^3.3.2",
+    "v8-coverage-merge": "^1.1.2",
     "v8-to-istanbul": "^1.2.0",
-    "yargs": "^10.0.3",
-    "yargs-parser": "^8.0.0"
+    "yargs": "^12.0.2",
+    "yargs-parser": "^10.1.0"
   },
   "devDependencies": {
-    "bundle-dependencies": "^1.0.2",
     "chai": "^4.1.2",
-    "mocha": "^4.0.1",
-    "nyc": "^11.4.1",
-    "standard": "^10.0.3",
-    "standard-version": "^4.2.0"
+    "mocha": "^5.2.0",
+    "standard": "^12.0.1",
+    "standard-version": "^4.4.0"
+  },
+  "engines": {
+    "node": ">=10.10.0"
   },
-  "bundledDependencies": [
-    "find-up",
-    "foreground-child",
-    "istanbul-lib-coverage",
-    "istanbul-lib-report",
-    "istanbul-reports",
-    "mkdirp",
-    "rimraf",
-    "signal-exit",
-    "spawn-wrap",
-    "test-exclude",
-    "uuid",
-    "v8-to-istanbul",
-    "yargs",
-    "yargs-parser"
+  "files": [
+    "lib",
+    "bin",
+    "LICENSE"
   ]
 }

test/fixtures/timeout.js → test/fixtures/async.js

@@ -1,5 +1,3 @@
-const a = 'apple' ? 'banana' : 'grape'
-
 function cool () {
 
 }

test/fixtures/multiple-spawn.js

@@ -0,0 +1,12 @@
+const {spawnSync} = require('child_process')
+{
+  const output = spawnSync(process.execPath, ['./test/fixtures/subprocess',
+                           '1'])
+  console.info(output.stdout.toString('utf8'))
+}
+
+{
+  const output = spawnSync(process.execPath, ['./test/fixtures/subprocess',
+                           '2'])
+  console.info(output.stdout.toString('utf8'))
+}

test/fixtures/normal.js

@@ -1,4 +1,4 @@
-require('./timeout')
+require('./async')
 
 console.info('i am a line of code')
 

test/fixtures/subprocess.js

@@ -0,0 +1,15 @@
+function first () {
+  console.info('first')
+}
+
+function second () {
+  console.info('second')
+}
+
+if (process.argv[2] === '1') {
+  first()
+}
+
+if (process.argv[2] === '2') {
+  second()
+}

test/integration.js

@@ -1,26 +1,40 @@
 /* global describe, it */
 
-const {spawnSync} = require('child_process')
+const { spawnSync } = require('child_process')
 const c8Path = require.resolve('../bin/c8')
 
 require('chai').should()
 
 describe('c8', () => {
   it('reports coverage for script that exits normally', () => {
-    const {output} = spawnSync(c8Path, [
+    const { output } = spawnSync(c8Path, [
+      '--exclude="test/*.js"',
       process.execPath,
       require.resolve('./fixtures/normal')
-    ], {
-      env: process.env,
-      cwd: process.cwd()
-    })
+    ])
     output.toString('utf8').should.include(`
-------------|----------|----------|----------|----------|----------------|
-File        |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
-------------|----------|----------|----------|----------|----------------|
-All files   |    91.67 |      100 |       80 |    91.67 |                |
- normal.js  |    85.71 |      100 |       50 |    85.71 |       14,15,16 |
- timeout.js |      100 |      100 |      100 |      100 |                |
-------------|----------|----------|----------|----------|----------------|`)
+-----------|----------|----------|----------|----------|-------------------|
+File       |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
+-----------|----------|----------|----------|----------|-------------------|
+All files  |    91.18 |    88.89 |        0 |    91.18 |                   |
+ async.js  |      100 |      100 |      100 |      100 |                   |
+ normal.js |    85.71 |       75 |        0 |    85.71 |          14,15,16 |
+-----------|----------|----------|----------|----------|-------------------|`)
+  })
+
+  it('merges reports from subprocesses together', () => {
+    const { output } = spawnSync(c8Path, [
+      '--exclude="test/*.js"',
+      process.execPath,
+      require.resolve('./fixtures/multiple-spawn')
+    ])
+    output.toString('utf8').should.include(`
+-------------------|----------|----------|----------|----------|-------------------|
+File               |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
+-------------------|----------|----------|----------|----------|-------------------|
+All files          |      100 |    77.78 |      100 |      100 |                   |
+ multiple-spawn.js |      100 |      100 |      100 |      100 |                   |
+ subprocess.js     |      100 |    71.43 |      100 |      100 |              9,13 |
+-------------------|----------|----------|----------|----------|-------------------|`)
   })
 })