feat: add support for 1:1 source-maps (#85)

BREAKING CHANGE: c8 will now load source-maps if possible and remap coverage accordingly

bin/c8.js

@@ -27,8 +27,8 @@ let argv = buildYargs().parse(instrumenterArgs)
     }
 
     process.env.NODE_V8_COVERAGE = argv.tempDirectory
-    foreground(hideInstrumenterArgs(argv), done => {
-      outputReport(argv)
+    foreground(hideInstrumenterArgs(argv), async (done) => {
+      await outputReport(argv)
       done()
     })
   }

lib/commands/check-coverage.js

@@ -25,14 +25,14 @@ exports.handler = function (argv) {
   exports.checkCoverages(argv, report)
 }
 
-exports.checkCoverages = function (argv, report) {
+exports.checkCoverages = async function (argv, report) {
   const thresholds = {
     lines: argv.lines,
     functions: argv.functions,
     branches: argv.branches,
     statements: argv.statements
   }
-  const map = report.getCoverageMapFromAllCoverageFiles()
+  const map = await report.getCoverageMapFromAllCoverageFiles()
   if (argv.perFile) {
     map.files().forEach(file => {
       checkCoverage(map.fileCoverageFor(file).toSummary(), thresholds, file)

lib/commands/report.js

@@ -5,11 +5,11 @@ exports.command = 'report'
 
 exports.describe = 'read V8 coverage data from temp and output report'
 
-exports.handler = function (argv) {
-  exports.outputReport(argv)
+exports.handler = async function (argv) {
+  await exports.outputReport(argv)
 }
 
-exports.outputReport = function (argv) {
+exports.outputReport = async function (argv) {
   const report = Report({
     include: argv.include,
     exclude: argv.exclude,
@@ -21,6 +21,6 @@ exports.outputReport = function (argv) {
     omitRelative: argv.omitRelative,
     wrapperLength: argv.wrapperLength
   })
-  report.run()
+  await report.run()
   if (argv.checkCoverage) checkCoverages(argv, report)
 }

lib/report.js

@@ -33,8 +33,8 @@ class Report {
     this.omitRelative = omitRelative
     this.wrapperLength = wrapperLength
   }
-  run () {
-    const map = this.getCoverageMapFromAllCoverageFiles()
+  async run () {
+    const map = await this.getCoverageMapFromAllCoverageFiles()
     var context = libReport.createContext({
       dir: this.reportsDirectory,
       watermarks: this.watermarks
@@ -47,7 +47,7 @@ class Report {
     })
   }
 
-  getCoverageMapFromAllCoverageFiles () {
+  async getCoverageMapFromAllCoverageFiles () {
     // the merge process can be very expensive, and it's often the case that
     // check-coverage is called immediately after a report. We memoize the
     // result from getCoverageMapFromAllCoverageFiles() to address this
@@ -61,9 +61,10 @@ class Report {
     for (const v8ScriptCov of v8ProcessCov.result) {
       try {
         const path = resolve(this.resolve, v8ScriptCov.url)
-        const script = v8toIstanbul(path, this.wrapperLength)
-        script.applyCoverage(v8ScriptCov.functions)
-        map.merge(script.toIstanbul())
+        const converter = v8toIstanbul(path, this.wrapperLength)
+        await converter.load()
+        converter.applyCoverage(v8ScriptCov.functions)
+        map.merge(converter.toIstanbul())
       } catch (err) {
         console.warn(`file: ${v8ScriptCov.url} error: ${err.stack}`)
       }

package.json

@@ -41,8 +41,7 @@
     "istanbul-reports": "^2.0.0",
     "rimraf": "^2.6.2",
     "test-exclude": "^5.0.0",
-    "uuid": "^3.3.2",
-    "v8-to-istanbul": "^2.0.4",
+    "v8-to-istanbul": "^3.0.1",
     "yargs": "^13.1.0",
     "yargs-parser": "^10.1.0"
   },

test/fixtures/source-maps/branches/branches.js

@@ -0,0 +1,20 @@
+if (false) {
+  console.info('unreachable')
+} else if (true) {
+  console.info('reachable')
+} else {
+  console.info('unreachable')
+}
+
+function branch (a) {
+  if (a) {
+    console.info('a = true')
+  } else if (undefined) {
+    console.info('unreachable')
+  } else {
+    console.info('a = false')
+  }
+}
+
+branch(true)
+branch(false)

test/fixtures/source-maps/branches/branches.typescript.ts

@@ -0,0 +1,25 @@
+enum ATrue {
+  IsTrue = 1,
+  IsFalse = 0
+}
+
+if (false) {
+  console.info('unreachable')
+} else if (true) {
+  console.info('reachable')
+} else {
+  console.info('unreachable')
+}
+
+function branch (a: boolean) {
+  if (a) {
+    console.info('a = true')
+  } else if (undefined) {
+    console.info('unreachable')
+  } else {
+    console.info('a = false')
+  }
+}
+
+branch(!!ATrue.IsTrue)
+branch(!!ATrue.IsFalse)

test/fixtures/source-maps/classes/classes.js

@@ -0,0 +1,27 @@
+class Foo {
+  constructor (x=33) {
+    this.x = x ? x : 99
+    if (this.x) {
+      console.info('covered')
+    } else {
+      console.info('uncovered')
+    }
+    this.methodC()
+  }
+  methodA () {
+    console.info('covered')
+  }
+  methodB () {
+    console.info('uncovered')
+  }
+  methodC () {
+    console.info('covered')
+  }
+  methodD () {
+    console.info('uncovered')
+  }
+}
+
+const a = new Foo(0)
+const b = new Foo(33)
+a.methodA()