implemented 6 more passing tests for range. Now works like python's range

test/collections.js

@@ -2,10 +2,6 @@ $(document).ready(function() {
 
   module("Collection functions (each, any, select, and so on...)");
 
-  test("generators: range", function() {
-    equals(_.range(4).join(' '), '0 1 2 3 4', 'range with positive number generates an array of of elements 0,1,2,...,n');
-  });
-
   test("collections: each", function() {
     _.each([1, 2, 3], function(num, i) {
       equals(num, i + 1, 'each iterators provide value and iteration count');

test/generators.js

@@ -0,0 +1,15 @@
+$(document).ready(function() {
+
+  module("Generator functions (range...)");
+
+  test("generators: range", function() {
+    equals(_.range(0).join(''), '', 'range with 0 as a first argument generates an empty array');
+    equals(_.range(4).join(' '), '0 1 2 3', 'range with a single positive argument generates an array of elements 0,1,2,...,n-1');
+    equals(_.range(5, 8).join(' '), '5 6 7', 'range with two arguments a & b, a<b generates an array of elements a,a+1,a+2,...,b-2,b-1');
+    equals(_.range(8, 5).join(''), '', 'range with two arguments a & b, b<a generates an empty array');
+    equals(_.range(3, 10, 3).join(' '), '3 6 9', 'range with three arguments a & b & c, c < b-a, a < b generates an array of elements a,a+c,a+2c,...,b - (multiplier of a) < c');
+    equals(_.range(3, 10, 15).join(''), '3', 'range with three arguments a & b & c, c > b-a, a < b generates an array with a single element, equal to a');
+    equals(_.range(12, 7, -2).join(' '), '12 10 8', 'range with three arguments a & b & c, a > b, c < 0 generates an array of elements a,a-c,a-2c and ends with the number not less than b');
+  });
+});
+

test/test.html

@@ -7,6 +7,7 @@
   <script type="text/javascript" src="vendor/qunit.js"></script>
   <script type="text/javascript" src="vendor/jslitmus.js"></script>
   <script type="text/javascript" src="../underscore.js"></script>
+  <script type="text/javascript" src="generators.js"></script>
   <script type="text/javascript" src="collections.js"></script>
   <script type="text/javascript" src="arrays.js"></script>
   <script type="text/javascript" src="functions.js"></script>
@@ -31,4 +32,4 @@
   </h2>
   <br />
 </body>
-</html>
+</html>

test/utility.js

@@ -36,7 +36,7 @@ $(document).ready(function() {
     "flatten", "foldl", "foldr", "forEach", "functions", "head", "identity", "include",
     "indexOf", "inject", "intersect", "invoke", "isArray", "isElement", "isEmpty", "isEqual",
     "isFunction", "isNumber", "isString", "isUndefined", "keys", "last", "lastIndexOf", "map", "max",
-    "methods", "min", "pluck", "reduce", "reduceRight", "reject", "rest", "select",
+    "methods", "min", "pluck", "range", "reduce", "reduceRight", "reject", "rest", "select",
     "size", "some", "sortBy", "sortedIndex", "tail", "template", "toArray", "uniq",
     "uniqueId", "values", "without", "wrap", "zip"];
     ok(_(expected).isEqual(_.methods()), 'provides a sorted list of functions');

underscore.js

@@ -33,19 +33,33 @@
   // Current version.
   _.VERSION = '0.4.5';
 
-  /*------------------------ Generator Functions: ----------------------------*/
-  _.range = function(upper, lower, step) {
-    if (!lower) var lower = 0;
-    if (!step) var step = 1;
+  /*------------------------ Generator Functions: ---------------------------*/
 
-    var result = new Array(((upper - lower) / step) + 1));
-
-    for (var i = lower; i <= upper; i += step) {
-        result[i] = i;
+  // Generates an Array, containing an arithmetic progressions
+  // Analog of python's built-in function 'range'
+  _.range = function(start, stop, step) {
+    if (!stop) {
+      var stop = start;
+      start = 0;
     }
 
-    return result;
-  }
+    if (!step) var step = 1;
+
+    var length = Math.ceil((stop - start) / step);
+
+    if (length < 0) {
+      return [];
+    }
+
+    var results = new Array(length);
+    var resIdx = 0;
+
+    for (var i = start; (start <= stop ? stop - i > 0 : i - stop > 0); i += step) {
+      results[resIdx++] = i;
+    }
+
+    return results;
+  };
 
   /*------------------------ Collection Functions: ---------------------------*/