Merge pull request #243 from Aweary/random-seed

[api] Implement faker.seed for deterministic output

4 files changed, 34 insertions, 18 deletions

diff --git a/lib/index.js b/lib/index.js
index 2ebd6028..5f179ae1 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -18,7 +18,7 @@
 */
 
 function Faker (opts) {
-  
+
   var self = this;
 
   opts = opts || {};
@@ -27,20 +27,19 @@ function Faker (opts) {
   var locales = self.locales || opts.locales || {};
   var locale = self.locale || opts.locale || "en";
   var localeFallback = self.localeFallback || opts.localeFallback || "en";
-  
+
   self.locales = locales;
   self.locale = locale;
   self.localeFallback = localeFallback;
-  
-  
+
   self.definitions = {};
-  
+
   var Fake = require('./fake');
   self.fake = new Fake(self).fake;
-  
+
   var Random = require('./random');
   self.random = new Random(self);
-  // self.random = require('./random');  
+  // self.random = require('./random');
 
   var Helpers = require('./helpers');
   self.helpers = new Helpers(self);
@@ -80,7 +79,7 @@ function Faker (opts) {
   self.commerce = new Commerce(self);
 
   // TODO: fix self.commerce = require('./commerce');
-  
+
   var _definitions = {
     "name": ["first_name", "last_name", "prefix", "suffix", "title", "male_first_name", "female_first_name", "male_middle_name", "female_middle_name", "male_last_name", "female_last_name"],
     "address": ["city_prefix", "city_suffix", "street_suffix", "county", "country", "country_code", "state", "state_abbr", "street_prefix", "postcode"],
@@ -123,8 +122,12 @@ function Faker (opts) {
       });
     });
   });
-  
-  
+
 };
 
-module['exports'] = Faker;
\ No newline at end of file
+Faker.prototype.seed = function(value) {
+  var Random = require('./random');
+  this.seedValue = value;
+  this.random = new Random(this, this.seedValue);
+}
+module['exports'] = Faker;
diff --git a/lib/random.js b/lib/random.js
index 2d37c551..fc7e54d9 100644
--- a/lib/random.js
+++ b/lib/random.js
@@ -1,7 +1,15 @@
 var mersenne = require('../vendor/mersenne');
 
-function Random (faker) {
-  
+function Random (faker, seed) {
+  // Use a user provided seed if it exists
+  if (seed) {
+    if (Array.isArray(seed) && seed.length) {
+      mersenne.seed_array(seed);
+    }
+    else {
+      mersenne.seed(seed);
+    }
+  }
   // returns a single random number based on a max number or range
   this.number = function (options) {
 
@@ -28,7 +36,7 @@ function Random (faker) {
     var max = options.max;
     if (max >= 0) {
       max += options.precision;
-    } 
+    }
 
     var randomNumber = options.precision * Math.floor(
       mersenne.rand(max / options.precision, options.min / options.precision));
diff --git a/test/random.unit.js b/test/random.unit.js
index 201c2267..8f047ee5 100644
--- a/test/random.unit.js
+++ b/test/random.unit.js
@@ -65,10 +65,16 @@ describe("random.js", function () {
       };
 
       faker.random.number(opts);
-      
+
       assert.equal(opts.min, min);
       assert.equal(opts.max, max);
     });
+
+    it('should return deterministic results when seeded', function() {
+      faker.seed(100);
+      var name = faker.name.findName();
+      assert.equal(name, 'Dulce Jenkins');
+    })
   });
 
   describe('arrayElement', function() {
diff --git a/vendor/mersenne.js b/vendor/mersenne.js
index 13c49639..33b08e2d 100644
--- a/vendor/mersenne.js
+++ b/vendor/mersenne.js
@@ -103,7 +103,7 @@ function MersenneTwister19937()
 		//c//mt[0]= s & 0xffffffff;
 		mt[0]= unsigned32(s & 0xffffffff);
 		for (mti=1; mti<N; mti++) {
-			mt[mti] = 
+			mt[mti] =
 			//c//(1812433253 * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
 			addition32(multiplication32(1812433253, unsigned32(mt[mti-1] ^ (mt[mti-1] >>> 30))), mti);
 			/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
@@ -133,7 +133,7 @@ function MersenneTwister19937()
 			//c//mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525))
 			//c//	+ init_key[j] + j; /* non linear */
 			mt[i] = addition32(addition32(unsigned32(mt[i] ^ multiplication32(unsigned32(mt[i-1] ^ (mt[i-1] >>> 30)), 1664525)), init_key[j]), j);
-			mt[i] = 
+			mt[i] =
 			//c//mt[i] &= 0xffffffff; /* for WORDSIZE > 32 machines */
 			unsigned32(mt[i] & 0xffffffff);
 			i++; j++;
@@ -284,4 +284,3 @@ exports.seed_array = function(A) {
         }
     gen.init_by_array(A);
 }
-