| // Copyright 2009 The Closure Library Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS-IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| goog.provide('goog.testing.PseudoRandomTest'); |
| goog.setTestOnly('goog.testing.PseudoRandomTest'); |
| |
| goog.require('goog.testing.PseudoRandom'); |
| goog.require('goog.testing.jsunit'); |
| |
| function runFairnessTest(sides, rolls, chiSquareLimit) { |
| // Initialize the count table for dice rolls. |
| var counts = []; |
| for (var i = 0; i < sides; ++i) { |
| counts[i] = 0; |
| } |
| // Roll the dice many times and count the results. |
| for (var i = 0; i < rolls; ++i) { |
| ++counts[Math.floor(Math.random() * sides)]; |
| } |
| // If the dice is fair, we expect a uniform distribution. |
| var expected = rolls / sides; |
| // Pearson's chi-square test for a distribution fit. |
| var chiSquare = 0; |
| for (var i = 0; i < sides; ++i) { |
| chiSquare += (counts[i] - expected) * (counts[i] - expected) / expected; |
| } |
| assert('Chi-square test for a distribution fit failed', |
| chiSquare < chiSquareLimit); |
| } |
| |
| function testInstall() { |
| var random = new goog.testing.PseudoRandom(); |
| var originalRandom = Math.random; |
| |
| assertFalse(!!random.installed_); |
| |
| random.install(); |
| assertTrue(random.installed_); |
| assertNotEquals(Math.random, originalRandom); |
| |
| random.uninstall(); |
| assertFalse(random.installed_); |
| assertEquals(originalRandom, Math.random); |
| } |
| |
| function testBounds() { |
| var random = new goog.testing.PseudoRandom(); |
| random.install(); |
| |
| for (var i = 0; i < 100000; ++i) { |
| var value = Math.random(); |
| assert('Random value out of bounds', value >= 0 && value < 1); |
| } |
| |
| random.uninstall(); |
| } |
| |
| function testFairness() { |
| var random = new goog.testing.PseudoRandom(0, true); |
| |
| // Chi-square statistics: p-value = 0.05, df = 5, limit = 11.07. |
| runFairnessTest(6, 100000, 11.07); |
| // Chi-square statistics: p-value = 0.05, df = 100, limit = 124.34. |
| runFairnessTest(101, 100000, 124.34); |
| |
| random.uninstall(); |
| } |
| |
| function testReseed() { |
| var random = new goog.testing.PseudoRandom(100, true); |
| |
| var sequence = []; |
| for (var i = 0; i < 64000; ++i) { |
| sequence.push(Math.random()); |
| } |
| |
| random.seed(100); |
| for (var i = 0; i < sequence.length; ++i) { |
| assertEquals(sequence[i], Math.random()); |
| } |
| |
| random.uninstall(); |
| } |