Add shlex.join method (#19)

Author: sfc-gh-kbregula

README.md

@@ -23,6 +23,14 @@ operators (such as `2>/dev/null`) or comments, and it does not perform variable
 
 ## Usage
 
+### `shlex.join()`
+
+```node
+var join = require("shlex").join
+join(["ls", "-al", '/'])  // returns: 'ls -al /'
+join([ 'rm', '-f', '/Volumes/Macintosh HD' ])  // returns: "rm -f '/Volumes/Macintosh HD'"
+```
+
 ### `shlex.quote()`
 
 ```node
@@ -37,5 +45,5 @@ quote("can't")    // returns: 'can'"'"'t'
 ```node
 var split = require("shlex").split
 split('ls -al /')  // returns: [ 'ls', '-al', '/' ]
-split('rm -f "/Volumes/Macintosh HD"')  // returns [ 'rm', '-f', '/Volumes/Macintosh HD' ]
+split('rm -f "/Volumes/Macintosh HD"')  // returns: [ 'rm', '-f', '/Volumes/Macintosh HD' ]
 ```

shlex.d.ts

@@ -1,2 +1,3 @@
-export function split(s: string): string[];
+export function join(args: string[]): string;
 export function quote(s: string): string;
+export function split(s: string): string[];

shlex.js

@@ -260,7 +260,8 @@ class Shlexer {
 
 
 /**
- * Splits a given string using shell-like syntax.
+ * Splits a given string using shell-like syntax. This function is the inverse
+ * of shlex.join().
  *
  * @param {String} s String to split.
  * @returns {String[]}
@@ -283,3 +284,21 @@ exports.quote = function (s) {
 
   return ('\'' + s.replace(/('+)/g, '\'"$1"\'') + '\'').replace(/^''|''$/g, '')
 }
+
+
+/**
+ * Concatenate the tokens of the list args and return a string. This function
+ * is the inverse of shlex.split().
+ *
+ * The returned value is shell-escaped to protect against injection
+ * vulnerabilities (see shlex.quote()).
+ *
+ * @param {String[]} args List of args to join
+ * @returns {String}
+*/
+exports.join = function (args) {
+  if (!Array.isArray(args)) {
+    throw new TypeError("args should be an array")
+  }
+  return args.map(exports.quote).join(" ")
+}

test/test.ts

@@ -4,5 +4,6 @@ shlex.quote('test text')
 shlex.split('test text "multi word thing"')
 
 // Should error
+shlex.join()
 shlex.quote()
 shlex.split()

test/test_join.js

@@ -0,0 +1,20 @@
+/* eslint-env mocha */
+'use strict'
+
+const { assert } = require('chai')
+const shlex = require('../shlex')
+
+describe('shlex.join()', () => {
+  const posixTestcases = [
+    [['ls', '-al', '/'], 'ls -al /'],
+    [['rm', '-f', '/Volumes/Macintosh HD'], "rm -f '/Volumes/Macintosh HD'"]
+  ]
+
+  it('should join according to POSIX rules', () => {
+    posixTestcases.forEach(function (test) {
+      const [input, expected] = test
+
+      assert.deepEqual(shlex.join(input), expected)
+    })
+  })
+})