fix: use uuid/v4 to generate unique identifiers. (#883)

index.js

@@ -12,7 +12,6 @@ const Hash = require('./lib/hash')
 const libCoverage = require('istanbul-lib-coverage')
 const libHook = require('istanbul-lib-hook')
 const libReport = require('istanbul-lib-report')
-const md5hex = require('md5-hex')
 const mkdirp = require('make-dir')
 const Module = require('module')
 const onExit = require('signal-exit')
@@ -22,6 +21,7 @@ const resolveFrom = require('resolve-from')
 const rimraf = require('rimraf')
 const SourceMaps = require('./lib/source-maps')
 const testExclude = require('test-exclude')
+const uuid = require('uuid/v4')
 
 var ProcessInfo
 try {
@@ -363,11 +363,7 @@ NYC.prototype.wrap = function (bin) {
   return this
 }
 
-NYC.prototype.generateUniqueID = function () {
-  return md5hex(
-    process.hrtime().concat(process.pid).map(String)
-  )
-}
+NYC.prototype.generateUniqueID = uuid
 
 NYC.prototype.writeCoverageFile = function () {
   var coverage = coverageFinder()

package.json

@@ -89,13 +89,13 @@
     "istanbul-lib-source-maps": "^2.0.0",
     "istanbul-reports": "^1.5.0",
     "make-dir": "^1.3.0",
-    "md5-hex": "^2.0.0",
     "merge-source-map": "^1.1.0",
     "resolve-from": "^4.0.0",
     "rimraf": "^2.6.2",
     "signal-exit": "^3.0.2",
     "spawn-wrap": "^1.4.2",
     "test-exclude": "^5.0.0",
+    "uuid": "^3.3.2",
     "yargs": "11.1.0",
     "yargs-parser": "^9.0.2"
   },
@@ -140,13 +140,13 @@
     "istanbul-lib-source-maps",
     "istanbul-reports",
     "make-dir",
-    "md5-hex",
     "merge-source-map",
     "resolve-from",
     "rimraf",
     "signal-exit",
     "spawn-wrap",
     "test-exclude",
+    "uuid",
     "yargs",
     "yargs-parser"
   ]