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<!DOCTYPE html>
<html>
<!--
Copyright 2009 The Closure Library Authors. All Rights Reserved.
Use of this source code is governed by the Apache License, Version 2.0.
See the COPYING file for details.
-->
<head>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Closure Unit Tests - goog.testing.PseudoRandom</title>
<script src="../base.js"></script>
<script>
goog.require('goog.testing.PseudoRandom');
goog.require('goog.testing.jsunit');
</script>
</head>
<body>
<script>
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();
}
</script>
</body>
</html>
|
