add faker.random.arrayElements

2 files changed, 68 insertions, 0 deletions

diff --git a/lib/random.js b/lib/random.js
index d3cbf3ea..6b5544da 100644
--- a/lib/random.js
+++ b/lib/random.js
@@ -67,6 +67,34 @@ function Random (faker, seed) {
   }
 
   /**
+   * takes an array and returns a subset with random elements of the array
+   *
+   * @method faker.random.arrayElement
+   * @param {array} array
+   * @param {number} count number of elements to pick
+   */
+  this.arrayElements = function (array, count) {
+      array = array || ["a", "b", "c"];
+
+      if (typeof count !== 'number') {
+        count = faker.random.number({ min: 1, max: array.length });
+      } else if (count > array.length) {
+        count = array.length;
+      } else if (count < 0) {
+        count = 0;
+      }
+
+      var arrayCopy = array.slice();
+      var countToRemove = arrayCopy.length - count;
+      for (var i = 0; i < countToRemove; i++) {
+        var indexToRemove = faker.random.number({ max: arrayCopy.length - 1 });
+        arrayCopy.splice(indexToRemove, 1);
+      }
+
+      return arrayCopy;
+  }
+
+  /**
    * takes an object and returns the randomly key or value
    *
    * @method faker.random.objectElement
diff --git a/test/random.unit.js b/test/random.unit.js
index 94a7167d..786cdc9b 100644
--- a/test/random.unit.js
+++ b/test/random.unit.js
@@ -89,6 +89,46 @@ describe("random.js", function () {
     });
   });
 
+  describe('arrayElements', function() {
+    it('returns a subset with random elements in the array', function() {
+      var testArray = ['hello', 'to', 'you', 'my', 'friend'];
+      var subset = faker.random.arrayElements(testArray);
+
+      // Check length
+      assert.ok(subset.length >= 1 && subset.length <= testArray.length);
+
+      // Check elements
+      subset.forEach(function(element) {
+        assert.ok(testArray.indexOf(element) > -1);
+      });
+
+      // Check uniqueness
+      subset.forEach(function(element) {
+        assert.ok(!this.hasOwnProperty(element));
+        this[element] = true;
+      }, {});
+    });
+
+    it('returns a subset of fixed length with random elements in the array', function() {
+      var testArray = ['hello', 'to', 'you', 'my', 'friend'];
+      var subset = faker.random.arrayElements(testArray, 3);
+
+      // Check length
+      assert.ok(subset.length === 3);
+
+      // Check elements
+      subset.forEach(function(element) {
+        assert.ok(testArray.indexOf(element) > -1);
+      });
+
+      // Check uniqueness
+      subset.forEach(function(element) {
+        assert.ok(!this.hasOwnProperty(element));
+        this[element] = true;
+      }, {});
+    });
+  });
+
   describe('UUID', function() {
     it('should generate a valid UUID', function() {
       var UUID = faker.random.uuid();