commons-numbers-core/src/test/java/org/apache/commons/numbers/core/ArithmeticUtilsTest.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.commons.numbers.core;

import java.util.Arrays;
import java.math.BigInteger;
import java.util.Collections;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

/**
 * Test cases for the {@link ArithmeticUtils} class.
 *
 */
class ArithmeticUtilsTest {

    @Test
    void testGcd() {
        int a = 30;
        int b = 50;
        int c = 77;

        Assertions.assertEquals(0, ArithmeticUtils.gcd(0, 0));

        Assertions.assertEquals(b, ArithmeticUtils.gcd(0, b));
        Assertions.assertEquals(a, ArithmeticUtils.gcd(a, 0));
        Assertions.assertEquals(b, ArithmeticUtils.gcd(0, -b));
        Assertions.assertEquals(a, ArithmeticUtils.gcd(-a, 0));

        Assertions.assertEquals(10, ArithmeticUtils.gcd(a, b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(-a, b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(a, -b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(-a, -b));

        Assertions.assertEquals(1, ArithmeticUtils.gcd(a, c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(-a, c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(a, -c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(-a, -c));

        Assertions.assertEquals(3 * (1 << 15), ArithmeticUtils.gcd(3 * (1 << 20), 9 * (1 << 15)));

        Assertions.assertEquals(Integer.MAX_VALUE, ArithmeticUtils.gcd(Integer.MAX_VALUE, 0));
        Assertions.assertEquals(Integer.MAX_VALUE, ArithmeticUtils.gcd(-Integer.MAX_VALUE, 0));
        Assertions.assertEquals(1 << 30, ArithmeticUtils.gcd(1 << 30, -Integer.MIN_VALUE));
        try {
            // gcd(Integer.MIN_VALUE, 0) > Integer.MAX_VALUE
            ArithmeticUtils.gcd(Integer.MIN_VALUE, 0);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
        try {
            // gcd(0, Integer.MIN_VALUE) > Integer.MAX_VALUE
            ArithmeticUtils.gcd(0, Integer.MIN_VALUE);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
        try {
            // gcd(Integer.MIN_VALUE, Integer.MIN_VALUE) > Integer.MAX_VALUE
            ArithmeticUtils.gcd(Integer.MIN_VALUE, Integer.MIN_VALUE);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
    }

    @Test
    void testGcdConsistency() {
        // Use Integer to prevent varargs vs array issue with Arrays.asList
        Integer[] primeList = {19, 23, 53, 67, 73, 79, 101, 103, 111, 131};

        for (int i = 0; i < 20; i++) {
            Collections.shuffle(Arrays.asList(primeList));
            int p1 = primeList[0];
            int p2 = primeList[1];
            int p3 = primeList[2];
            int p4 = primeList[3];
            int i1 = p1 * p2 * p3;
            int i2 = p1 * p2 * p4;
            int gcd = p1 * p2;
            Assertions.assertEquals(gcd, ArithmeticUtils.gcd(i1, i2));
            long l1 = i1;
            long l2 = i2;
            Assertions.assertEquals(gcd, ArithmeticUtils.gcd(l1, l2));
        }
    }

    @Test
    void  testGcdLong() {
        long a = 30;
        long b = 50;
        long c = 77;

        Assertions.assertEquals(0, ArithmeticUtils.gcd(0L, 0));

        Assertions.assertEquals(b, ArithmeticUtils.gcd(0, b));
        Assertions.assertEquals(a, ArithmeticUtils.gcd(a, 0));
        Assertions.assertEquals(b, ArithmeticUtils.gcd(0, -b));
        Assertions.assertEquals(a, ArithmeticUtils.gcd(-a, 0));

        Assertions.assertEquals(10, ArithmeticUtils.gcd(a, b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(-a, b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(a, -b));
        Assertions.assertEquals(10, ArithmeticUtils.gcd(-a, -b));

        Assertions.assertEquals(1, ArithmeticUtils.gcd(a, c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(-a, c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(a, -c));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(-a, -c));

        Assertions.assertEquals(3L * (1L << 45), ArithmeticUtils.gcd(3L * (1L << 50), 9L * (1L << 45)));

        Assertions.assertEquals(1L << 45, ArithmeticUtils.gcd(1L << 45, Long.MIN_VALUE));

        Assertions.assertEquals(Long.MAX_VALUE, ArithmeticUtils.gcd(Long.MAX_VALUE, 0L));
        Assertions.assertEquals(Long.MAX_VALUE, ArithmeticUtils.gcd(-Long.MAX_VALUE, 0L));
        Assertions.assertEquals(1, ArithmeticUtils.gcd(60247241209L, 153092023L));
        try {
            // gcd(Long.MIN_VALUE, 0) > Long.MAX_VALUE
            ArithmeticUtils.gcd(Long.MIN_VALUE, 0);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
        try {
            // gcd(0, Long.MIN_VALUE) > Long.MAX_VALUE
            ArithmeticUtils.gcd(0, Long.MIN_VALUE);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
        try {
            // gcd(Long.MIN_VALUE, Long.MIN_VALUE) > Long.MAX_VALUE
            ArithmeticUtils.gcd(Long.MIN_VALUE, Long.MIN_VALUE);
            Assertions.fail("expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
    }


    @Test
    void testLcm() {
        int a = 30;
        int b = 50;
        int c = 77;

        Assertions.assertEquals(0, ArithmeticUtils.lcm(0, b));
        Assertions.assertEquals(0, ArithmeticUtils.lcm(a, 0));
        Assertions.assertEquals(b, ArithmeticUtils.lcm(1, b));
        Assertions.assertEquals(a, ArithmeticUtils.lcm(a, 1));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(a, b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(-a, b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(a, -b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(-a, -b));
        Assertions.assertEquals(2310, ArithmeticUtils.lcm(a, c));

        // Assert that no intermediate value overflows:
        // The naive implementation of lcm(a,b) would be (a*b)/gcd(a,b)
        Assertions.assertEquals((1 << 20) * 15, ArithmeticUtils.lcm((1 << 20) * 3, (1 << 20) * 5));

        // Special case
        Assertions.assertEquals(0, ArithmeticUtils.lcm(0, 0));

        try {
            // lcm == abs(MIN_VALUE) cannot be represented as a nonnegative int
            ArithmeticUtils.lcm(Integer.MIN_VALUE, 1);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }

        try {
            // lcm == abs(MIN_VALUE) cannot be represented as a nonnegative int
            ArithmeticUtils.lcm(Integer.MIN_VALUE, 1 << 20);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }

        try {
            ArithmeticUtils.lcm(Integer.MAX_VALUE, Integer.MAX_VALUE - 1);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
    }

    @Test
    void testLcmLong() {
        long a = 30;
        long b = 50;
        long c = 77;

        Assertions.assertEquals(0, ArithmeticUtils.lcm(0, b));
        Assertions.assertEquals(0, ArithmeticUtils.lcm(a, 0));
        Assertions.assertEquals(b, ArithmeticUtils.lcm(1, b));
        Assertions.assertEquals(a, ArithmeticUtils.lcm(a, 1));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(a, b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(-a, b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(a, -b));
        Assertions.assertEquals(150, ArithmeticUtils.lcm(-a, -b));
        Assertions.assertEquals(2310, ArithmeticUtils.lcm(a, c));

        Assertions.assertEquals(Long.MAX_VALUE, ArithmeticUtils.lcm(60247241209L, 153092023L));

        // Assert that no intermediate value overflows:
        // The naive implementation of lcm(a,b) would be (a*b)/gcd(a,b)
        Assertions.assertEquals((1L << 50) * 15, ArithmeticUtils.lcm((1L << 45) * 3, (1L << 50) * 5));

        // Special case
        Assertions.assertEquals(0L, ArithmeticUtils.lcm(0L, 0L));

        try {
            // lcm == abs(MIN_VALUE) cannot be represented as a nonnegative int
            ArithmeticUtils.lcm(Long.MIN_VALUE, 1);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }

        try {
            // lcm == abs(MIN_VALUE) cannot be represented as a nonnegative int
            ArithmeticUtils.lcm(Long.MIN_VALUE, 1 << 20);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }

        Assertions.assertEquals((long) Integer.MAX_VALUE * (Integer.MAX_VALUE - 1),
            ArithmeticUtils.lcm((long)Integer.MAX_VALUE, Integer.MAX_VALUE - 1));
        try {
            ArithmeticUtils.lcm(Long.MAX_VALUE, Long.MAX_VALUE - 1);
            Assertions.fail("Expecting ArithmeticException");
        } catch (ArithmeticException expected) {
            // expected
        }
    }

    @Test
    void testPow() {

        Assertions.assertEquals(1801088541, ArithmeticUtils.pow(21, 7));
        Assertions.assertEquals(1, ArithmeticUtils.pow(21, 0));
        try {
            ArithmeticUtils.pow(21, -7);
            Assertions.fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // expected behavior
        }

        Assertions.assertEquals(1801088541, ArithmeticUtils.pow(21, 7));
        Assertions.assertEquals(1, ArithmeticUtils.pow(21, 0));
        try {
            ArithmeticUtils.pow(21, -7);
            Assertions.fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // expected behavior
        }

        Assertions.assertEquals(1801088541L, ArithmeticUtils.pow(21L, 7));
        Assertions.assertEquals(1L, ArithmeticUtils.pow(21L, 0));
        try {
            ArithmeticUtils.pow(21L, -7);
            Assertions.fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // expected behavior
        }

        BigInteger twentyOne = BigInteger.valueOf(21L);
        Assertions.assertEquals(BigInteger.valueOf(1801088541L), ArithmeticUtils.pow(twentyOne, 7));
        Assertions.assertEquals(BigInteger.ONE, ArithmeticUtils.pow(twentyOne, 0));
        try {
            ArithmeticUtils.pow(twentyOne, -7);
            Assertions.fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // expected behavior
        }

        Assertions.assertEquals(BigInteger.valueOf(1801088541L), ArithmeticUtils.pow(twentyOne, 7L));
        Assertions.assertEquals(BigInteger.ONE, ArithmeticUtils.pow(twentyOne, 0L));
        try {
            ArithmeticUtils.pow(twentyOne, -7L);
            Assertions.fail("Expecting IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            // expected behavior
        }

        Assertions.assertEquals(BigInteger.valueOf(1801088541L), ArithmeticUtils.pow(twentyOne, BigInteger.valueOf(7L)));
        Assertions.assertEquals(BigInteger.ONE, ArithmeticUtils.pow(twentyOne, BigInteger.ZERO));
        Assertions.assertThrows(IllegalArgumentException.class, () ->
            ArithmeticUtils.pow(twentyOne, BigInteger.valueOf(-7L)));

        BigInteger bigOne =
            new BigInteger("1543786922199448028351389769265814882661837148" +
                           "4763915343722775611762713982220306372888519211" +
                           "560905579993523402015636025177602059044911261");
        Assertions.assertEquals(bigOne, ArithmeticUtils.pow(twentyOne, 103));
        Assertions.assertEquals(bigOne, ArithmeticUtils.pow(twentyOne, 103L));
        Assertions.assertEquals(bigOne, ArithmeticUtils.pow(twentyOne, BigInteger.valueOf(103L)));

    }

    @Test
    void testPowIntOverflow() {
        Assertions.assertThrows(ArithmeticException.class,
            () -> ArithmeticUtils.pow(21, 8)
        );
    }

    @Test
    void testPowInt() {
        final int base = 21;

        Assertions.assertEquals(85766121L,
                            ArithmeticUtils.pow(base, 6));
        Assertions.assertEquals(1801088541L,
                            ArithmeticUtils.pow(base, 7));
    }

    @Test
    void testPowNegativeIntOverflow() {
        Assertions.assertThrows(ArithmeticException.class,
            () -> ArithmeticUtils.pow(-21, 8)
        );
    }

    @Test
    void testPowNegativeInt() {
        final int base = -21;

        Assertions.assertEquals(85766121,
                            ArithmeticUtils.pow(base, 6));
        Assertions.assertEquals(-1801088541,
                            ArithmeticUtils.pow(base, 7));
    }

    @Test
    void testPowMinusOneInt() {
        final int base = -1;
        for (int i = 0; i < 100; i++) {
            final int pow = ArithmeticUtils.pow(base, i);
            Assertions.assertEquals(i % 2 == 0 ? 1 : -1, pow, "i: " + i);
        }
    }

    @Test
    void testPowOneInt() {
        final int base = 1;
        for (int i = 0; i < 100; i++) {
            final int pow = ArithmeticUtils.pow(base, i);
            Assertions.assertEquals(1, pow, "i: " + i);
        }
    }

    @Test
    void testPowLongOverflow() {
        Assertions.assertThrows(ArithmeticException.class,
            () -> ArithmeticUtils.pow(21, 15)
        );
    }

    @Test
    void testPowLong() {
        final long base = 21;

        Assertions.assertEquals(154472377739119461L,
                            ArithmeticUtils.pow(base, 13));
        Assertions.assertEquals(3243919932521508681L,
                            ArithmeticUtils.pow(base, 14));
    }

    @Test
    void testPowNegativeLongOverflow() {
        Assertions.assertThrows(ArithmeticException.class,
            () -> ArithmeticUtils.pow(-21L, 15)
        );
    }

    @Test
    void testPowNegativeLong() {
        final long base = -21;

        Assertions.assertEquals(-154472377739119461L,
                            ArithmeticUtils.pow(base, 13));
        Assertions.assertEquals(3243919932521508681L,
                            ArithmeticUtils.pow(base, 14));
    }

    @Test
    void testPowMinusOneLong() {
        final long base = -1;
        for (int i = 0; i < 100; i++) {
            final long pow = ArithmeticUtils.pow(base, i);
            Assertions.assertEquals(i % 2 == 0 ? 1 : -1, pow, "i: " + i);
        }
    }

    @Test
    void testPowOneLong() {
        final long base = 1;
        for (int i = 0; i < 100; i++) {
            final long pow = ArithmeticUtils.pow(base, i);
            Assertions.assertEquals(1, pow, "i: " + i);
        }
    }

    @Test
    void testPowEdgeCases() {
        Assertions.assertEquals(0, ArithmeticUtils.pow(0, 2));
        Assertions.assertEquals(0L, ArithmeticUtils.pow(0L, 2));
        Assertions.assertEquals(0, ArithmeticUtils.pow(0, 1));
        Assertions.assertEquals(0L, ArithmeticUtils.pow(0L, 1));
        Assertions.assertEquals(1, ArithmeticUtils.pow(0, 0));
        Assertions.assertEquals(1L, ArithmeticUtils.pow(0L, 0));

        for (int i = 20; i <= 35; i++) {
            final int ti = i;
            Assertions.assertThrows(ArithmeticException.class, () -> ArithmeticUtils.pow(3, ti));
        }
        for (int i = 40; i <= 70; i++) {
            final int ti = i;
            Assertions.assertThrows(ArithmeticException.class, () -> ArithmeticUtils.pow(3L, ti));
        }
    }

    @Test
    void testIsPowerOfTwo() {
        final int n = 1025;
        final boolean[] expected = new boolean[n];
        Arrays.fill(expected, false);
        for (int i = 1; i < expected.length; i *= 2) {
            expected[i] = true;
        }
        for (int i = 0; i < expected.length; i++) {
            final boolean actual = ArithmeticUtils.isPowerOfTwo(i);
            Assertions.assertEquals(expected[i], actual, Integer.toString(i));
        }
    }

    /**
     * Testing helper method.
     * @return an array of int numbers containing corner cases:<ul>
     * <li>values near the beginning of int range,</li>
     * <li>values near the end of int range,</li>
     * <li>values near zero</li>
     * <li>and some randomly distributed values.</li>
     * </ul>
     */
    private static int[] getIntSpecialCases() {
        int[] ints = new int[100];
        int i = 0;
        ints[i++] = Integer.MAX_VALUE;
        ints[i++] = Integer.MAX_VALUE - 1;
        ints[i++] = 100;
        ints[i++] = 101;
        ints[i++] = 102;
        ints[i++] = 300;
        ints[i++] = 567;
        for (int j = 0; j < 20; j++) {
            ints[i++] = j;
        }
        for (int j = i - 1; j >= 0; j--) {
            ints[i++] = ints[j] > 0 ? -ints[j] : Integer.MIN_VALUE;
        }
        java.util.Random r = new java.util.Random(System.nanoTime());
        for (; i < ints.length;) {
            ints[i++] = r.nextInt();
        }
        return ints;
    }

    /**
     * Testing helper method.
     * @return an array of long numbers containing corner cases:<ul>
     * <li>values near the beginning of long range,</li>
     * <li>values near the end of long range,</li>
     * <li>values near the beginning of int range,</li>
     * <li>values near the end of int range,</li>
     * <li>values near zero</li>
     * <li>and some randomly distributed values.</li>
     * </ul>
     */
    private static long[] getLongSpecialCases() {
        long[] longs = new long[100];
        int i = 0;
        longs[i++] = Long.MAX_VALUE;
        longs[i++] = Long.MAX_VALUE - 1L;
        longs[i++] = (long) Integer.MAX_VALUE + 1L;
        longs[i++] = Integer.MAX_VALUE;
        longs[i++] = Integer.MAX_VALUE - 1;
        longs[i++] = 100L;
        longs[i++] = 101L;
        longs[i++] = 102L;
        longs[i++] = 300L;
        longs[i++] = 567L;
        for (int j = 0; j < 20; j++) {
            longs[i++] = j;
        }
        for (int j = i - 1; j >= 0; j--) {
            longs[i++] = longs[j] > 0L ? -longs[j] : Long.MIN_VALUE;
        }
        java.util.Random r = new java.util.Random(System.nanoTime());
        for (; i < longs.length;) {
            longs[i++] = r.nextLong();
        }
        return longs;
    }

    private static long toUnsignedLong(int number) {
        return number < 0 ? 0x100000000L + (long)number : (long)number;
    }

    private static int remainderUnsignedExpected(int dividend, int divisor) {
        return (int)remainderUnsignedExpected(toUnsignedLong(dividend), toUnsignedLong(divisor));
    }

    private static int divideUnsignedExpected(int dividend, int divisor) {
        return (int)divideUnsignedExpected(toUnsignedLong(dividend), toUnsignedLong(divisor));
    }

    private static BigInteger toUnsignedBigInteger(long number) {
        return number < 0L ? BigInteger.ONE.shiftLeft(64).add(BigInteger.valueOf(number)) : BigInteger.valueOf(number);
    }

    private static long remainderUnsignedExpected(long dividend, long divisor) {
        return toUnsignedBigInteger(dividend).remainder(toUnsignedBigInteger(divisor)).longValue();
    }

    private static long divideUnsignedExpected(long dividend, long divisor) {
        return toUnsignedBigInteger(dividend).divide(toUnsignedBigInteger(divisor)).longValue();
    }

    @Test
    void testRemainderUnsignedInt() {
        Assertions.assertEquals(36, ArithmeticUtils.remainderUnsigned(-2147479015, 63));
        Assertions.assertEquals(6, ArithmeticUtils.remainderUnsigned(-2147479015, 25));
    }

    @Test
    void testRemainderUnsignedIntSpecialCases() {
        int[] ints = getIntSpecialCases();
        for (int dividend : ints) {
            for (int divisor : ints) {
                if (divisor == 0) {
                    Assertions.assertThrows(ArithmeticException.class,
                        () -> ArithmeticUtils.remainderUnsigned(dividend, divisor)
                    );
                } else {
                    Assertions.assertEquals(remainderUnsignedExpected(dividend, divisor), ArithmeticUtils.remainderUnsigned(dividend, divisor));
                }
            }
        }
    }

    @Test
    void testRemainderUnsignedLong() {
        Assertions.assertEquals(48L, ArithmeticUtils.remainderUnsigned(-2147479015L, 63L));
    }

    @Test
    void testRemainderUnsignedLongSpecialCases() {
        long[] longs = getLongSpecialCases();
        for (long dividend : longs) {
            for (long divisor : longs) {
                if (divisor == 0L) {
                    try {
                        ArithmeticUtils.remainderUnsigned(dividend, divisor);
                        Assertions.fail("Should have failed with ArithmeticException: division by zero");
                    } catch (ArithmeticException e) {
                        // Success.
                    }
                } else {
                    Assertions.assertEquals(remainderUnsignedExpected(dividend, divisor), ArithmeticUtils.remainderUnsigned(dividend, divisor));
                }
            }
        }
    }

    @Test
    void testDivideUnsignedInt() {
        Assertions.assertEquals(34087115, ArithmeticUtils.divideUnsigned(-2147479015, 63));
        Assertions.assertEquals(85899531, ArithmeticUtils.divideUnsigned(-2147479015, 25));
        Assertions.assertEquals(2147483646, ArithmeticUtils.divideUnsigned(-3, 2));
        Assertions.assertEquals(330382098, ArithmeticUtils.divideUnsigned(-16, 13));
        Assertions.assertEquals(306783377, ArithmeticUtils.divideUnsigned(-16, 14));
        Assertions.assertEquals(2, ArithmeticUtils.divideUnsigned(-1, 2147483647));
        Assertions.assertEquals(2, ArithmeticUtils.divideUnsigned(-2, 2147483647));
        Assertions.assertEquals(1, ArithmeticUtils.divideUnsigned(-3, 2147483647));
        Assertions.assertEquals(1, ArithmeticUtils.divideUnsigned(-16, 2147483647));
        Assertions.assertEquals(1, ArithmeticUtils.divideUnsigned(-16, 2147483646));
    }

    @Test
    void testDivideUnsignedIntSpecialCases() {
        int[] ints = getIntSpecialCases();
        for (int dividend : ints) {
            for (int divisor : ints) {
                if (divisor == 0) {
                    Assertions.assertThrows(ArithmeticException.class,
                        () -> ArithmeticUtils.divideUnsigned(dividend, divisor)
                    );
                } else {
                    Assertions.assertEquals(divideUnsignedExpected(dividend, divisor), ArithmeticUtils.divideUnsigned(dividend, divisor));
                }
            }
        }
    }

    @Test
    void testDivideUnsignedLong() {
        Assertions.assertEquals(292805461453366231L, ArithmeticUtils.divideUnsigned(-2147479015L, 63L));
    }

    @Test
    void testDivideUnsignedLongSpecialCases() {
        long[] longs = getLongSpecialCases();
        for (long dividend : longs) {
            for (long divisor : longs) {
                if (divisor == 0L) {
                    Assertions.assertThrows(ArithmeticException.class,
                        () -> ArithmeticUtils.divideUnsigned(dividend, divisor)
                    );
                } else {
                    Assertions.assertEquals(divideUnsignedExpected(dividend, divisor), ArithmeticUtils.divideUnsigned(dividend, divisor));
                }
            }
        }
    }
}