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