refactor: Increasing code coverage of lib/parse-args.js to 100%. (bco…

…e#447)

test: Adding a test case for NODE_V8_COVERAGE and changing the describe block title. (bcoe#447)

lib/parse-args.js

@@ -5,9 +5,11 @@ const { readFileSync } = require('fs')
 const Yargs = require('yargs/yargs')
 const { applyExtends } = require('yargs/helpers')
 const parser = require('yargs-parser')
-const { resolve } = require('path')
 
 function buildYargs (withCommands = false) {
+  if (typeof process.env.NODE_V8_COVERAGE !== 'string') {
+    process.env.NODE_V8_COVERAGE = process.cwd() + '/coverage/tmp'
+  }
   const yargs = Yargs([])
     .usage('$0 [opts] [script] [opts]')
     .options('config', {
@@ -126,7 +128,8 @@ function buildYargs (withCommands = false) {
     })
     .option('temp-directory', {
       describe: 'directory V8 coverage data is written to and read from',
-      default: process.env.NODE_V8_COVERAGE
+      default: process.env.NODE_V8_COVERAGE,
+      type: 'string'
     })
     .option('clean', {
       default: true,
@@ -154,12 +157,6 @@ function buildYargs (withCommands = false) {
     })
     .pkgConf('c8')
     .demandCommand(1)
-    .check((argv) => {
-      if (!argv.tempDirectory) {
-        argv.tempDirectory = resolve(argv.reportsDir, 'tmp')
-      }
-      return true
-    })
     .epilog('visit https://git.io/vHysA for list of available reporters')
 
   // TODO: enable once yargs upgraded to v17: https://github.com/bcoe/c8/pull/332#discussion_r721636191
@@ -191,18 +188,13 @@ function buildYargs (withCommands = false) {
 function hideInstrumenterArgs (yargv) {
   let argv = process.argv.slice(1)
   argv = argv.slice(argv.indexOf(yargv._[0]))
-  if (argv[0][0] === '-') {
-    argv.unshift(process.execPath)
-  }
   return argv
 }
 
 function hideInstrumenteeArgs () {
   let argv = process.argv.slice(2)
   const yargv = parser(argv)
 
-  if (!yargv._.length) return argv
-
   // drop all the arguments after the bin being
   // instrumented by c8.
   argv = argv.slice(0, argv.indexOf(yargv._[0]))