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cicirellocicirello
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refactored tests
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‎src/test/java/org/cicirello/permutations/PermutationConstructorRelatedTests.java

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/*
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* JavaPermutationTools: A Java library for computation on permutations and sequences
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* Copyright 2005-2022 Vincent A. Cicirello, <https://www.cicirello.org/>.
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*
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* This file is part of JavaPermutationTools (https://jpt.cicirello.org/).
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*
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* JavaPermutationTools is free software: you can
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* redistribute it and/or modify it under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your
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* option) any later version.
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*
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* JavaPermutationTools is distributed in the hope
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* that it will be useful, but WITHOUT ANY WARRANTY; without even
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* the implied warranty of MERCHANTABILITY or FITNESS FOR A
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* PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with JavaPermutationTools. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.cicirello.permutations;
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import java.util.SplittableRandom;
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import java.util.Random;
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import java.math.BigInteger;
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import org.junit.jupiter.api.*;
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import static org.junit.jupiter.api.Assertions.*;
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/**
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* JUnit tests for the constructors and methods of the Permutation class.
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*/
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public class PermutationConstructorRelatedTests extends SharedTestHelpersPermutation {
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// Set to false to enable chi square tests for randomness of constructor and
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// scramble, specifically for the constructor and scramble that uses ThreadLocalRandom
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// since it is not seedable. Tests passed repeatedly as of last update.
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// If that constructor or scramble is updated, then this flag should be set false to enable
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// tests (and reset true after passing).
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// Note: This doesn't disable those tests for the constructors/scramble methods
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// that use a source of randomness that is seedable.
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private static final boolean disableChiSquareTests = true;
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@Test
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public void testZeroLengthPermutations() {
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// different ways of constructing 0 length permutations.
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Permutation p1 = new Permutation(0);
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Permutation p2 = new Permutation(new int[] {});
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Permutation p3 = new Permutation(0,0);
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Permutation copy = new Permutation(p1);
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// the above 4 should all be equivalent, so check
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assertEquals(p1,p2);
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assertEquals(p1,p3);
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assertEquals(p1,copy);
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assertEquals(p2,p3);
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assertEquals(p2,copy);
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assertEquals(p3,copy);
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}
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@Test
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public void testPermutationConstructor() {
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for (int n = 1; n <= 10; n++) {
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for (int i = 0; i < 10; i++) {
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Permutation p = new Permutation(n);
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validatePermutation(p, n);
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}
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}
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SplittableRandom r = new SplittableRandom();
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for (int n = 1; n <= 10; n++) {
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for (int i = 0; i < 10; i++) {
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Permutation p = new Permutation(n, r);
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validatePermutation(p, n);
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}
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}
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}
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@Test
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public void testPermutationConstructorSpecific() {
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int fact = 1;
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for (int n = 1; n <= 6; n++) {
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fact *= n;
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for (int i = 0; i < fact; i++) {
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Permutation p = new Permutation(n, i);
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assertEquals(i, p.toInteger());
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assertEquals(BigInteger.valueOf(i), p.toBigInteger());
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validatePermutation(p, n);
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}
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}
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int n = 12;
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fact = 1;
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for (int i = 2; i <= n; i++) {
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fact *= i;
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}
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SplittableRandom r = new SplittableRandom();
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for (int i = 0; i < 100; i++) {
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int which = r.nextInt(fact);
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Permutation p = new Permutation(n, which);
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assertEquals(which, p.toInteger());
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assertEquals(BigInteger.valueOf(which), p.toBigInteger());
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validatePermutation(p, n);
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}
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}
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@Test
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public void testPermutationConstructorSpecificBigInt() {
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int fact = 1;
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for (int n = 1; n <= 6; n++) {
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fact *= n;
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for (int i = 0; i < fact; i++) {
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BigInteger big = BigInteger.valueOf(i);
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Permutation p = new Permutation(n, big);
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assertEquals(i, p.toInteger());
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assertEquals(big, p.toBigInteger());
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validatePermutation(p, n);
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}
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}
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int n = 12;
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fact = 1;
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for (int i = 2; i <= n; i++) {
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fact *= i;
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}
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SplittableRandom r = new SplittableRandom();
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for (int i = 0; i < 100; i++) {
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int which = r.nextInt(fact);
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BigInteger bigWhich = BigInteger.valueOf(which);
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Permutation p = new Permutation(n, bigWhich);
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assertEquals(which, p.toInteger());
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assertEquals(bigWhich, p.toBigInteger());
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validatePermutation(p, n);
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}
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n = 20;
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BigInteger f = BigInteger.ONE;
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for (int i = 2; i <= n; i++) {
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f = f.multiply(BigInteger.valueOf(i));
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}
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for (int i = 0; i < 20; i++) {
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BigInteger bigWhich = new BigInteger(f.bitLength()-1, new Random(42));
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Permutation p = new Permutation(n, bigWhich);
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assertEquals(bigWhich, p.toBigInteger());
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validatePermutation(p, n);
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}
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}
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@Test
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public void testToIntegerExceptions() {
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UnsupportedOperationException thrown = assertThrows(
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UnsupportedOperationException.class,
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() -> (new Permutation(13)).toInteger()
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);
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}
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@Test
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public void testPermutationCopyConstructor() {
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for (int n = 1; n <= 10; n++) {
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for (int i = 0; i < 10; i++) {
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Permutation p = new Permutation(n);
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Permutation copy = new Permutation(p);
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assertEquals(p, copy);
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assertEquals(p.hashCode(), copy.hashCode());
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}
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}
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}
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@Test
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public void testPermutationCopyMethod() {
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for (int n = 1; n <= 10; n++) {
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for (int i = 0; i < 10; i++) {
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Permutation p = new Permutation(n);
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Permutation copy = p.copy();
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assertEquals(p, copy);
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assertTrue(p != copy);
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assertEquals(p.hashCode(), copy.hashCode());
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}
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}
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}
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@Test
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public void testPermutationEqualsSpecialCases() {
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Permutation p = new Permutation(5);
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assertTrue(p.equals(p));
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assertFalse(p.equals(null));
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assertFalse(p.equals("hello"));
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}
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@Test
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public void testPermutationConstructorCopyPartial() {
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for (int n = 1; n <= 10; n++) {
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int[] forward = new int[n];
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int[] backward = new int[n];
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for (int i = 0; i < n; i++) {
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backward[n-1-i] = forward[i] = i;
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}
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Permutation p1 = new Permutation(forward);
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Permutation p2 = new Permutation(backward);
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for (int m = 0; m <= n; m++) {
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Permutation copy1 = new Permutation(p1, m);
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Permutation copy2 = new Permutation(p2, m);
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assertEquals(m, copy1.length());
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assertEquals(m, copy2.length());
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validatePermutation(copy1, m);
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validatePermutation(copy2, m);
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for (int i = 0; i < m; i++) {
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assertEquals(i, copy1.get(i));
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assertEquals(m-1-i, copy2.get(i));
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}
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}
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}
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}
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@Test
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public void testPermutationEquals() {
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Permutation p = new Permutation(10);
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for (int n = 1; n < 10; n++) {
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Permutation partialCopy = new Permutation(p, n);
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assertNotEquals(p, partialCopy);
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}
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Permutation copy = new Permutation(p);
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assertEquals(p, copy);
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assertNotEquals(new Permutation(new int[] {0, 1, 2, 3}), new Permutation(new int[] {3, 1, 2, 0}));
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}
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@Test
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public void testUniformityOfConstructors() {
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final int N = 12000;
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SplittableRandom r2 = new SplittableRandom(42);
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int tooHigh0 = 0;
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int tooHigh2 = 0;
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for (int k = 0; k < 100; k++) {
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int[] counts0 = new int[120];
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int[] counts2 = new int[120];
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for (int i = 0; i < N; i++) {
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Permutation p0 = new Permutation(5);
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Permutation p2 = new Permutation(5, r2);
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int j0 = p0.toInteger();
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int j2 = p2.toInteger();
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counts0[j0]++;
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counts2[j2]++;
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}
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if (chiSquare(counts0) > 146.567) tooHigh0++;
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if (chiSquare(counts2) > 146.567) tooHigh2++;
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}
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if (!disableChiSquareTests) {
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assertTrue(tooHigh0 <= 10);
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}
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assertTrue(tooHigh2 <= 10);
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}
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}

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