__set__ returns an 'undo' function that when invoked will restore the module to the values it had before it was called

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/__set__.js b/lib/__set__.js
index 66e8c0a..0fa88ac 100644
--- a/lib/__set__.js
+++ b/lib/__set__.js
@@ -11,10 +11,12 @@
  * @throws {ReferenceError} When the variable is unknown
  * @return {*}
  */
+
 function __set__() {
     arguments.varName = arguments[0];
     arguments.varValue = arguments[1];
     arguments.src = "";
+    var snapshot = {};
 
     if (typeof arguments[0] === "object" && arguments.length === 1) {
         arguments.env = arguments.varName;
@@ -25,6 +27,7 @@ function __set__() {
             if (arguments.env.hasOwnProperty(arguments.varName)) {
                 arguments.varValue = arguments.env[arguments.varName];
                 arguments.src += arguments.varName + " = arguments.env." + arguments.varName + "; ";
+                snapshot[arguments.varName] = eval(arguments.varName);
             }
         }
     } else if (typeof arguments.varName === "string" && arguments.length === 2) {
@@ -32,11 +35,15 @@ function __set__() {
             throw new TypeError("__set__ expects a non-empty string as a variable name");
         }
         arguments.src = arguments.varName + " = arguments.varValue;";
+        snapshot[arguments.varName] = eval(arguments.varName);
     } else {
         throw new TypeError("__set__ expects an environment object or a non-empty string as a variable name");
     }
 
     eval(arguments.src);
+    return function() {
+      __set__(snapshot);
+    };
 }
 
-module.exports = __set__;
\ No newline at end of file
+module.exports = __set__;