feat: Node 11 no longer wraps scripts by default

.travis.yml

@@ -1,4 +1,4 @@
 language: node_js
 node_js:
-  - "10.10"
+  - "11"
 after_success: npm run coverage

lib/script.js

@@ -4,11 +4,12 @@ const CovBranch = require('./branch')
 const CovLine = require('./line')
 const CovFunction = require('./function')
 
-// Injected when Node.js is loading script into isolate.
-// see: https://github.com/nodejs/node/pull/21573.
-const cjsWrapperLength = require('module').wrapper[0].length
-
 const isWindows = process.platform === 'win32'
+const isNode10 = !!process.version.match(/^v10/)
+
+// Injected when Node.js is loading script into isolate pre Node 11.
+// see: https://github.com/nodejs/node/pull/21573.
+const cjsWrapperLength = isNode10 ? require('module').wrapper[0].length : 0
 
 module.exports = class CovScript {
   constructor (scriptPath, wrapperLength) {
@@ -17,19 +18,22 @@ module.exports = class CovScript {
     const source = fs.readFileSync(path, 'utf8')
     this.path = path
     this.wrapperLength = wrapperLength === undefined ? cjsWrapperLength : wrapperLength
-    this.wrapperLength -= shebangLength(source)
+    const shebangLength = getShebangLength(source)
+    this.wrapperLength -= shebangLength
     this.lines = []
     this.branches = []
     this.functions = []
     this.eof = -1
-    this._buildLines(source, this.lines)
+    this._buildLines(source, this.lines, shebangLength)
   }
-  _buildLines (source, lines) {
+  _buildLines (source, lines, shebangLength) {
     let position = 0
     const separator = isWindows ? '\r\n' : '\n'
-    source.split(separator).forEach((lineStr, i) => {
+    ;(source.trim()).split(separator).forEach((lineStr, i) => {
       this.eof = position + lineStr.length
-      lines.push(new CovLine(i + 1, position, this.eof))
+      const line = new CovLine(i + 1, position, this.eof)
+      if (i === 0 && shebangLength !== 0) line.count = 1
+      lines.push(line)
       position += lineStr.length + separator.length
     })
   }
@@ -135,7 +139,7 @@ module.exports = class CovScript {
   }
 }
 
-function shebangLength (source) {
+function getShebangLength (source) {
   if (source.indexOf('#!') === 0) {
     const match = source.match(/(?<shebang>#!.*)/)
     if (match) {