Added first Duplicate to Coding Challenges.

Author: ratracegrad

firstDuplicate/firstDuplicate.js

@@ -0,0 +1,23 @@
+/***************************************************************
+ *                                                             *
+ *                       CodePrep.io                           *
+ *                                                             *
+ *   Function:  firstDuplicate(str)                            *
+ *   Input:    1 string parameter                              *
+ *   Output:   String                                          *
+ *                                                             *
+ *   Output expectations:                                      *
+ *   var myTest = firstDuplicate('abcdefabcdeg');              *
+ *   console.log(myTest); // a                                 *
+ *                                                             *
+ *                                                             *
+ *   Write the code for the firstDuplicate function that       *
+ *   accepts a string as input and returns the first           *
+ *   character that is duplicated.                             *
+ *                                                             *
+ **************************************************************/
+
+var firstDuplicate = function(str) {
+    /* YOUR CODE GOES HERE */
+
+}

firstDuplicate/firstDuplicate.test.js

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+var should = require('should');
+var vm = require('vm');
+var fs = require('fs');
+var filename = __filename.replace(/\.test\.js$/, '.js');
+vm.runInThisContext(fs.readFileSync(filename), filename);
+
+
+describe('firstDuplicate', function() {
+    it('should exist', function(){
+        should.exist(firstDuplicate);
+    });
+
+    it('should be a function', function() {
+        firstDuplicate.should.be.a.Function;
+    });
+
+    it('should return a String', function() {
+        var result = firstDuplicate('aa');
+        should.exist(result);
+        result.should.be.an.instanceof(String);
+    });
+
+    it('should return an empty string if no input provided', function() {
+        var result = firstDuplicate();
+        result.should.be.eql('');
+    });
+
+    it('should return an empty string if only one character inputted', function(){
+        var result = firstDuplicate('a');
+        result.should.be.eql('');
+    });
+
+    it('should have the right answer', function(){
+        var result = firstDuplicate('abcdefabcdef');
+        result.should.be.eql('a');
+    });
+
+    it('should handle upper and lower case letters', function(){
+        var result = firstDuplicate('ABCDEFabcdef');
+        result.should.be.eql('a');
+    });
+
+    it('should handle long strings', function() {
+        var result = firstDuplicate('abcdefghijklmnopqrstuvwxyza');
+        result.should.be.eql('a');
+    });
+
+});

firstDuplicate/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "CodePrep.io_coding_challenges",
+  "author": "Jennifer Bland",
+  "url": "http://www.codeprep.io",
+  "version": "1.0.0",
+  "description": "CodePrep.io presents coding challenges you might face when interviewing for a Full-Stack Developer position",
+  "scripts": {
+    "test": "node ../node_modules/mocha/bin/mocha ./*.test.js"
+  }
+}