feat: Node API

README.md

@@ -26,4 +26,18 @@ Before running your application c8 creates [an inspector session](https://nodejs
 
 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/).
+[Istanbul's reporters](https://istanbul.js.org/).
+
+
+## Node API
+
+```js
+const {run, report} = require('c8')
+
+run(argv, async () => {
+  // run your code
+}).then(reports => report({
+  reports,
+  reporter: ['text', 'lcov']
+}))
+```

index.js

@@ -0,0 +1,4 @@
+'use strict'
+
+exports.run = require('./lib/run')
+exports.report = require('./lib/report')

lib/report.js

@@ -5,8 +5,9 @@ const {readdirSync, readFileSync} = require('fs')
 const {resolve} = require('path')
 
 class Report {
-  constructor ({reporter, coverageDirectory, watermarks}) {
+  constructor ({reporter, reports, coverageDirectory, watermarks}) {
     this.reporter = reporter
+    this.reports = reports
     this.coverageDirectory = coverageDirectory
     this.watermarks = watermarks
   }
@@ -33,6 +34,8 @@ class Report {
     return map
   }
   _loadReports () {
+    if (this.reports) return this.reports
+
     const tmpDirctory = resolve(this.coverageDirectory, './tmp')
     const files = readdirSync(tmpDirctory)
 

lib/run.js

@@ -0,0 +1,75 @@
+'use strict'
+
+const Exclude = require('test-exclude')
+const inspector = require('inspector')
+const { isAbsolute } = require('path')
+const v8ToIstanbul = require('v8-to-istanbul')
+
+module.exports = async function (argv, cb) {
+  const exclude = Exclude({
+    include: argv.include,
+    exclude: argv.exclude
+  })
+
+  const session = bootstrap()
+
+  const done = () => {
+    return onExit(session, { exclude, argv })
+  }
+
+  const cbResult = cb()
+  if (cbResult.then) {
+    return cbResult.then(done)
+  } else {
+    throw new Error('Callback needs to return a promise')
+  }
+}
+
+function bootstrap () {
+  // bootstrap the inspector before kicking
+  // off the user's code.
+  inspector.open(0, true)
+  const session = new inspector.Session()
+  session.connect()
+
+  session.post('Profiler.enable')
+  session.post('Runtime.enable')
+  session.post(
+    'Profiler.startPreciseCoverage', { callCount: true, detailed: true }
+  )
+  return session
+}
+
+function onExit (session, opts) {
+  return new Promise((resolve, reject) => {
+    session.post('Profiler.takePreciseCoverage', (err, res) => {
+      if (err) reject(err)
+      else {
+        try {
+          const result = getIstanbulFormatCoverage(filterResult(res.result, opts))
+          resolve(result)
+        } catch (err) {
+          reject(err)
+        }
+      }
+    })
+  })
+}
+
+function filterResult (result, { exclude }) {
+  result = result.filter(({ url }) => {
+    url = url.replace('file://', '')
+    return isAbsolute(url) &&
+      exclude.shouldInstrument(url) &&
+      url !== __filename
+  })
+  return result
+}
+
+function getIstanbulFormatCoverage (allV8Coverage) {
+  return allV8Coverage.map((v8) => {
+    const script = v8ToIstanbul(v8.url)
+    script.applyCoverage(v8.functions)
+    return script.toIstanbul()
+  })
+}

lib/wrap.js

@@ -1,80 +1,31 @@
 #!/usr/bin/env node
 'use strict'
 
-const Exclude = require('test-exclude')
-const inspector = require('inspector')
-const {isAbsolute} = require('path')
+const { writeFileSync } = require('fs')
+const { resolve } = require('path')
 const onExit = require('signal-exit')
-const {resolve} = require('path')
 const sw = require('spawn-wrap')
 const uuid = require('uuid')
-const v8ToIstanbul = require('v8-to-istanbul')
-const {writeFileSync} = require('fs')
+const run = require('./run')
 
 const argv = JSON.parse(process.env.C8_ARGV)
 
-const exclude = Exclude({
-  include: argv.include,
-  exclude: argv.exclude
-})
+wrap()
 
-;(async function runInstrumented () {
-  try {
-    // bootstrap the inspector before kicking
-    // off the user's code.
-    inspector.open(0, true)
-    const session = new inspector.Session()
-    session.connect()
-
-    session.post('Profiler.enable')
-    session.post('Runtime.enable')
-    session.post(
-      'Profiler.startPreciseCoverage',
-      {callCount: true, detailed: true}
-    )
-
-    // hook process.exit() and common exit signals, e.g., SIGTERM,
-    // and output coverage report when these occur.
-    onExit(() => {
-      session.post('Profiler.takePreciseCoverage', (err, res) => {
-        if (err) console.warn(err.message)
-        else {
-          try {
-            const result = filterResult(res.result)
-            writeIstanbulFormatCoverage(result)
-          } catch (err) {
-            console.warn(err.message)
-          }
-        }
-      })
-    }, {alwaysLast: true})
-
-    // run the user's actual application.
+async function wrap () {
+  const result = await run(argv, async () => {
     sw.runMain()
-  } catch (err) {
-    console.error(err)
-    process.exit(1)
-  }
-})()
-
-function filterResult (result) {
-  result = result.filter(({url}) => {
-    url = url.replace('file://', '')
-    return isAbsolute(url) &&
-      exclude.shouldInstrument(url) &&
-      url !== __filename
+    return new Promise((resolve) => onExit(resolve, { alwaysLast: true }))
   })
-  return result
+  write(result, { argv })
 }
 
-function writeIstanbulFormatCoverage (allV8Coverage) {
-  const tmpDirctory = resolve(argv.coverageDirectory, './tmp')
-  allV8Coverage.forEach((v8) => {
-    const script = v8ToIstanbul(v8.url)
-    script.applyCoverage(v8.functions)
+function write (coverage, { argv }) {
+  const tmpDirectory = resolve(argv.coverageDirectory, './tmp')
+  coverage.forEach((istanbul) => {
     writeFileSync(
-      resolve(tmpDirctory, `./${uuid.v4()}.json`),
-      JSON.stringify(script.toIstanbul(), null, 2),
+      resolve(tmpDirectory, `./${uuid.v4()}.json`),
+      JSON.stringify(istanbul, null, 2),
       'utf8'
     )
   })

test/integration.js

@@ -15,12 +15,15 @@ describe('c8', () => {
       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 Lines |
+---------------|----------|----------|----------|----------|----------------|
+All files      |    47.14 |       80 |        0 |    47.14 |                |
+ lib           |        0 |      100 |      100 |        0 |                |
+  wrap.js      |        0 |      100 |      100 |        0 |... 31,32,33,34 |
+ test/fixtures |    91.67 |       80 |        0 |    91.67 |                |
+  normal.js    |    85.71 |       75 |        0 |    85.71 |       14,15,16 |
+  timeout.js   |      100 |    83.33 |      100 |      100 |              1 |
+---------------|----------|----------|----------|----------|----------------|`)
   })
 })