feat: initial support for source-maps (#19)

BREAKING CHANGE: v8-to-istanbul is now async, making it possible to use the latest source-map library

Author: Benjamin E. Coe

README.md

@@ -10,12 +10,12 @@ converts from v8 coverage format to [istanbul's coverage format](https://github.
 
 ```js
 const v8toIstanbul = require('v8-to-istanbul')
-// create a script object from a source-file. the source file
-// is loaded from disk and this is used to determine the original
-// line count.
-const script = v8toIstanbul('./path-to-instrumented-file.js')
+// the path to the original source-file is required, as its contents are
+// used during the conversion algorithm.
+const converter = v8toIstanbul('./path-to-instrumented-file.js')
+await converter.load() // this is required due to the async source-map dependency.
 // provide an array of coverage information in v8 format.
-script.applyCoverage([
+converter.applyCoverage([
   {
     "functionName": "",
     "ranges": [
@@ -31,7 +31,7 @@ script.applyCoverage([
 ])
 // output coverage information in a form that can
 // be consumed by Istanbul.
-console.info(JSON.stringify(script.toIstanbul()))
+console.info(JSON.stringify(converter.toIstanbul()))
 ```
 
 ## Testing

index.js

@@ -1,5 +1,5 @@
-const Script = require('./lib/script')
+const V8ToIstanbul = require('./lib/v8-to-istanbul')
 
 module.exports = function (path, wrapperLength) {
-  return new Script(path, wrapperLength)
+  return new V8ToIstanbul(path, wrapperLength)
 }

lib/branch.js

@@ -9,17 +9,17 @@ module.exports = class CovBranch {
   toIstanbul () {
     const location = {
       start: {
-        line: this.startLine.line,
-        column: this.startCol - this.startLine.startCol
+        line: this.startLine,
+        column: this.startCol
       },
       end: {
-        line: this.endLine.line,
-        column: this.endCol - this.endLine.startCol
+        line: this.endLine,
+        column: this.endCol
       }
     }
     return {
       type: 'branch',
-      line: this.line,
+      line: this.startLine,
       loc: location,
       locations: [Object.assign({}, location)]
     }

lib/function.js

@@ -10,19 +10,19 @@ module.exports = class CovFunction {
   toIstanbul () {
     const loc = {
       start: {
-        line: this.startLine.line,
-        column: this.startCol - this.startLine.startCol
+        line: this.startLine,
+        column: this.startCol
       },
       end: {
-        line: this.endLine.line,
-        column: this.endCol - this.endLine.startCol
+        line: this.endLine,
+        column: this.endCol
       }
     }
     return {
       name: this.name,
       decl: loc,
       loc: loc,
-      line: this.startLine.line
+      line: this.startLine
     }
   }
 }

lib/line.js

@@ -1,9 +1,19 @@
 module.exports = class CovLine {
-  constructor (line, startCol, endCol) {
+  constructor (line, startCol, lineStr) {
     this.line = line
+    // note that startCol and endCol are absolute positions
+    // within a file, not relative to the line.
     this.startCol = startCol
-    this.endCol = endCol
-    this.count = 0
+
+    // the line length itself does not include the newline characters,
+    // these are however taken into account when enumerating absolute offset.
+    const matchedNewLineChar = lineStr.match(/\r?\n$/u)
+    const newLineLength = matchedNewLineChar ? matchedNewLineChar[0].length : 0
+    this.endCol = startCol + lineStr.length - newLineLength
+
+    // we start with all lines having been executed, and work
+    // backwards zeroing out lines based on V8 output.
+    this.count = 1
   }
   toIstanbul () {
     return {

lib/pathutils.js

@@ -0,0 +1,19 @@
+/*
+ Copyright 2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+
+// pulled from: https://github.com/istanbuljs/istanbuljs
+'use strict'
+
+const path = require('path')
+
+module.exports = {
+  isAbsolute: path.isAbsolute,
+  relativeTo (file, origFile) {
+    const p = path.isAbsolute(file)
+      ? file
+      : path.resolve(path.dirname(origFile), file)
+    return path.relative(process.cwd(), p)
+  }
+}