From 902f92ab5b10e02ad23461f76fbf69cba4f5bb7c Mon Sep 17 00:00:00 2001
From: Nate Fischer <ntfschr@gmail.com>
Date: Mon, 8 Aug 2016 11:44:16 -0700
Subject: [PATCH] feat: add overWrite option for commands (#503)

* feat: add overWrite option for commands

* fix: throws an error if a command is overwritten
---
 src/common.js  | 6 ++++++
 test/plugin.js | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/src/common.js b/src/common.js
index 5b5cd9f..919aee2 100644
--- a/src/common.js
+++ b/src/common.js
@@ -372,6 +372,7 @@ var DEFAULT_WRAP_OPTIONS = {
   pipeOnly: false,
   unix: true,
   wrapOutput: true,
+  overWrite: false,
 };
 
 // Register a new ShellJS command
@@ -379,6 +380,11 @@ function _register(name, implementation, wrapOptions) {
   wrapOptions = wrapOptions || {};
   // If an option isn't specified, use the default
   wrapOptions = objectAssign({}, DEFAULT_WRAP_OPTIONS, wrapOptions);
+
+  if (shell[name] && !wrapOptions.overWrite) {
+    throw new Error('unable to overwrite `' + name + '` command');
+  }
+
   if (wrapOptions.pipeOnly) {
     wrapOptions.canReceivePipe = true;
     shellMethods[name] = wrap(name, implementation, wrapOptions);
diff --git a/test/plugin.js b/test/plugin.js
index bcc9c62..42a7830 100644
--- a/test/plugin.js
+++ b/test/plugin.js
@@ -96,4 +96,11 @@ assert.equal(ret.stdout, '');
 assert.equal(ret.stderr, 'foo: Exited with code 5');
 assert.equal(shell.error(), 'foo: Exited with code 5');
 
+// Cannot overwrite an existing command by default
+var oldCat = shell.cat;
+assert.throws(function () {
+  plugin.register('cat', fooImplementation);
+}, 'Error: unable to overwrite `cat` command');
+assert.equal(shell.cat, oldCat);
+
 shell.exit(123);