SplittableRandomTest.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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import org.testng.Assert;
import org.testng.annotations.Test;

import java.util.SplittableRandom;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.LongAdder;
import java.util.function.BiConsumer;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertNotNull;
import static org.testng.AssertJUnit.assertTrue;

/**
 * @test
 * @run testng SplittableRandomTest
 * @run testng/othervm -Djava.util.secureRandomSeed=true SplittableRandomTest
 * @summary test methods on SplittableRandom
 * @key randomness
 */
@Test
public class SplittableRandomTest {

    // Note: this test was copied from the 166 TCK SplittableRandomTest test
    // and modified to be a TestNG test

    /*
     * Testing coverage notes:
     *
     * 1. Many of the test methods are adapted from ThreadLocalRandomTest.
     *
     * 2. These tests do not check for random number generator quality.
     * But we check for minimal API compliance by requiring that
     * repeated calls to nextX methods, up to NCALLS tries, produce at
     * least two distinct results. (In some possible universe, a
     * "correct" implementation might fail, but the odds are vastly
     * less than that of encountering a hardware failure while running
     * the test.) For bounded nextX methods, we sample various
     * intervals across multiples of primes. In other tests, we repeat
     * under REPS different values.
     */

    // max numbers of calls to detect getting stuck on one value
    static final int NCALLS = 10000;

    // max sampled int bound
    static final int MAX_INT_BOUND = (1 << 28);

    // max sampled long bound
    static final long MAX_LONG_BOUND = (1L << 42);

    // Number of replications for other checks
    static final int REPS = 20;

    /**
     * Repeated calls to nextInt produce at least two distinct results
     */
    public void testNextInt() {
        SplittableRandom sr = new SplittableRandom();
        int f = sr.nextInt();
        int i = 0;
        while (i < NCALLS && sr.nextInt() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextLong produce at least two distinct results
     */
    public void testNextLong() {
        SplittableRandom sr = new SplittableRandom();
        long f = sr.nextLong();
        int i = 0;
        while (i < NCALLS && sr.nextLong() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Repeated calls to nextDouble produce at least two distinct results
     */
    public void testNextDouble() {
        SplittableRandom sr = new SplittableRandom();
        double f = sr.nextDouble();
        int i = 0;
        while (i < NCALLS && sr.nextDouble() == f)
            ++i;
        assertTrue(i < NCALLS);
    }

    /**
     * Two SplittableRandoms created with the same seed produce the
     * same values for nextLong.
     */
    public void testSeedConstructor() {
        for (long seed = 2; seed < MAX_LONG_BOUND; seed += 15485863)  {
            SplittableRandom sr1 = new SplittableRandom(seed);
            SplittableRandom sr2 = new SplittableRandom(seed);
            for (int i = 0; i < REPS; ++i)
                assertEquals(sr1.nextLong(), sr2.nextLong());
        }
    }

    /**
     * A SplittableRandom produced by split() of a default-constructed
     * SplittableRandom generates a different sequence
     */
    public void testSplit1() {
        SplittableRandom sr = new SplittableRandom();
        for (int reps = 0; reps < REPS; ++reps) {
            SplittableRandom sc = sr.split();
            int i = 0;
            while (i < NCALLS && sr.nextLong() == sc.nextLong())
                ++i;
            assertTrue(i < NCALLS);
        }
    }

    /**
     * A SplittableRandom produced by split() of a seeded-constructed
     * SplittableRandom generates a different sequence
     */
    public void testSplit2() {
        SplittableRandom sr = new SplittableRandom(12345);
        for (int reps = 0; reps < REPS; ++reps) {
            SplittableRandom sc = sr.split();
            int i = 0;
            while (i < NCALLS && sr.nextLong() == sc.nextLong())
                ++i;
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextInt(negative) throws IllegalArgumentException
     */
    @Test(expectedExceptions = IllegalArgumentException.class)
    public void testNextIntBoundedNeg() {
        SplittableRandom sr = new SplittableRandom();
        int f = sr.nextInt(-17);
    }

    /**
     * nextInt(least >= bound) throws IllegalArgumentException
     */
    @Test(expectedExceptions = IllegalArgumentException.class)
    public void testNextIntBadBounds() {
        SplittableRandom sr = new SplittableRandom();
        int f = sr.nextInt(17, 2);
    }

    /**
     * nextInt(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded() {
        SplittableRandom sr = new SplittableRandom();
        // sample bound space across prime number increments
        for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
            int f = sr.nextInt(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            int j;
            while (i < NCALLS &&
                   (j = sr.nextInt(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextInt(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextIntBounded2() {
        SplittableRandom sr = new SplittableRandom();
        for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
            for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
                int f = sr.nextInt(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                int j;
                while (i < NCALLS &&
                       (j = sr.nextInt(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextLong(negative) throws IllegalArgumentException
     */
    @Test(expectedExceptions = IllegalArgumentException.class)
    public void testNextLongBoundedNeg() {
        SplittableRandom sr = new SplittableRandom();
        long f = sr.nextLong(-17);
    }

    /**
     * nextLong(least >= bound) throws IllegalArgumentException
     */
    @Test(expectedExceptions = IllegalArgumentException.class)
    public void testNextLongBadBounds() {
        SplittableRandom sr = new SplittableRandom();
        long f = sr.nextLong(17, 2);
    }

    /**
     * nextLong(bound) returns 0 <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded() {
        SplittableRandom sr = new SplittableRandom();
        for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
            long f = sr.nextLong(bound);
            assertTrue(0 <= f && f < bound);
            int i = 0;
            long j;
            while (i < NCALLS &&
                   (j = sr.nextLong(bound)) == f) {
                assertTrue(0 <= j && j < bound);
                ++i;
            }
            assertTrue(i < NCALLS);
        }
    }

    /**
     * nextLong(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextLongBounded2() {
        SplittableRandom sr = new SplittableRandom();
        for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
            for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
                long f = sr.nextLong(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                long j;
                while (i < NCALLS &&
                       (j = sr.nextLong(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * nextDouble(bound) throws IllegalArgumentException
     */
    public void testNextDoubleBadBound() {
        SplittableRandom sr = new SplittableRandom();
        executeAndCatchIAE(() -> sr.nextDouble(0.0));
        executeAndCatchIAE(() -> sr.nextDouble(-0.0));
        executeAndCatchIAE(() -> sr.nextDouble(+0.0));
        executeAndCatchIAE(() -> sr.nextDouble(-1.0));
        executeAndCatchIAE(() -> sr.nextDouble(Double.NaN));
        executeAndCatchIAE(() -> sr.nextDouble(Double.NEGATIVE_INFINITY));

        // Returns Double.MAX_VALUE
//        executeAndCatchIAE(() -> r.nextDouble(Double.POSITIVE_INFINITY));
    }

    /**
     * nextDouble(origin, bound) throws IllegalArgumentException
     */
    public void testNextDoubleBadOriginBound() {
        testDoubleBadOriginBound(new SplittableRandom()::nextDouble);
    }

    // An arbitrary finite double value
    static final double FINITE = Math.PI;

    void testDoubleBadOriginBound(BiConsumer<Double, Double> bi) {
        executeAndCatchIAE(() -> bi.accept(17.0, 2.0));
        executeAndCatchIAE(() -> bi.accept(0.0, 0.0));
        executeAndCatchIAE(() -> bi.accept(Double.NaN, FINITE));
        executeAndCatchIAE(() -> bi.accept(FINITE, Double.NaN));
        executeAndCatchIAE(() -> bi.accept(Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY));

        // Returns NaN
//        executeAndCatchIAE(() -> bi.accept(Double.NEGATIVE_INFINITY, FINITE));
//        executeAndCatchIAE(() -> bi.accept(Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY));

        executeAndCatchIAE(() -> bi.accept(FINITE, Double.NEGATIVE_INFINITY));

        // Returns Double.MAX_VALUE
//        executeAndCatchIAE(() -> bi.accept(FINITE, Double.POSITIVE_INFINITY));

        executeAndCatchIAE(() -> bi.accept(Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY));
        executeAndCatchIAE(() -> bi.accept(Double.POSITIVE_INFINITY, FINITE));
        executeAndCatchIAE(() -> bi.accept(Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY));
    }

    /**
     * nextDouble(least, bound) returns least <= value < bound;
     * repeated calls produce at least two distinct results
     */
    public void testNextDoubleBounded2() {
        SplittableRandom sr = new SplittableRandom();
        for (double least = 0.0001; least < 1.0e20; least *= 8) {
            for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
                double f = sr.nextDouble(least, bound);
                assertTrue(least <= f && f < bound);
                int i = 0;
                double j;
                while (i < NCALLS &&
                       (j = sr.nextDouble(least, bound)) == f) {
                    assertTrue(least <= j && j < bound);
                    ++i;
                }
                assertTrue(i < NCALLS);
            }
        }
    }

    /**
     * Invoking sized ints, long, doubles, with negative sizes throws
     * IllegalArgumentException
     */
    public void testBadStreamSize() {
        SplittableRandom r = new SplittableRandom();
        executeAndCatchIAE(() -> r.ints(-1L));
        executeAndCatchIAE(() -> r.ints(-1L, 2, 3));
        executeAndCatchIAE(() -> r.longs(-1L));
        executeAndCatchIAE(() -> r.longs(-1L, -1L, 1L));
        executeAndCatchIAE(() -> r.doubles(-1L));
        executeAndCatchIAE(() -> r.doubles(-1L, .5, .6));
    }

    /**
     * Invoking bounded ints, long, doubles, with illegal bounds throws
     * IllegalArgumentException
     */
    public void testBadStreamBounds() {
        SplittableRandom r = new SplittableRandom();
        executeAndCatchIAE(() -> r.ints(2, 1));
        executeAndCatchIAE(() -> r.ints(10, 42, 42));
        executeAndCatchIAE(() -> r.longs(-1L, -1L));
        executeAndCatchIAE(() -> r.longs(10, 1L, -2L));

        testDoubleBadOriginBound((o, b) -> r.doubles(10, o, b));
    }

    private void executeAndCatchIAE(Runnable r) {
        executeAndCatch(IllegalArgumentException.class, r);
    }

    private void executeAndCatch(Class<? extends Exception> expected, Runnable r) {
        Exception caught = null;
        try {
            r.run();
        }
        catch (Exception e) {
            caught = e;
        }

        assertNotNull(caught,
                      String.format("No Exception was thrown, expected an Exception of %s to be thrown",
                                    expected.getName()));
        Assert.assertTrue(expected.isInstance(caught),
                          String.format("Exception thrown %s not an instance of %s",
                                        caught.getClass().getName(), expected.getName()));
    }

    /**
     * A parallel sized stream of ints generates the given number of values
     */
    public void testIntsCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 0;
        for (int reps = 0; reps < REPS; ++reps) {
            counter.reset();
            r.ints(size).parallel().forEach(x -> {counter.increment();});
            assertEquals(counter.sum(), size);
            size += 524959;
        }
    }

    /**
     * A parallel sized stream of longs generates the given number of values
     */
    public void testLongsCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 0;
        for (int reps = 0; reps < REPS; ++reps) {
            counter.reset();
            r.longs(size).parallel().forEach(x -> {counter.increment();});
            assertEquals(counter.sum(), size);
            size += 524959;
        }
    }

    /**
     * A parallel sized stream of doubles generates the given number of values
     */
    public void testDoublesCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 0;
        for (int reps = 0; reps < REPS; ++reps) {
            counter.reset();
            r.doubles(size).parallel().forEach(x -> {counter.increment();});
            assertEquals(counter.sum(), size);
            size += 524959;
        }
    }

    /**
     * Each of a parallel sized stream of bounded ints is within bounds
     */
    public void testBoundedInts() {
        AtomicInteger fails = new AtomicInteger(0);
        SplittableRandom r = new SplittableRandom();
        long size = 12345L;
        for (int least = -15485867; least < MAX_INT_BOUND; least += 524959) {
            for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 67867967) {
                final int lo = least, hi = bound;
                r.ints(size, lo, hi).parallel().
                    forEach(x -> {if (x < lo || x >= hi)
                                fails.getAndIncrement(); });
            }
        }
        assertEquals(fails.get(), 0);
    }

    /**
     * Each of a parallel sized stream of bounded longs is within bounds
     */
    public void testBoundedLongs() {
        AtomicInteger fails = new AtomicInteger(0);
        SplittableRandom r = new SplittableRandom();
        long size = 123L;
        for (long least = -86028121; least < MAX_LONG_BOUND; least += 1982451653L) {
            for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
                final long lo = least, hi = bound;
                r.longs(size, lo, hi).parallel().
                    forEach(x -> {if (x < lo || x >= hi)
                                fails.getAndIncrement(); });
            }
        }
        assertEquals(fails.get(), 0);
    }

    /**
     * Each of a parallel sized stream of bounded doubles is within bounds
     */
    public void testBoundedDoubles() {
        AtomicInteger fails = new AtomicInteger(0);
        SplittableRandom r = new SplittableRandom();
        long size = 456;
        for (double least = 0.00011; least < 1.0e20; least *= 9) {
            for (double bound = least * 1.0011; bound < 1.0e20; bound *= 17) {
                final double lo = least, hi = bound;
                r.doubles(size, lo, hi).parallel().
                    forEach(x -> {if (x < lo || x >= hi)
                                fails.getAndIncrement(); });
            }
        }
        assertEquals(fails.get(), 0);
    }

    /**
     * A parallel unsized stream of ints generates at least 100 values
     */
    public void testUnsizedIntsCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.ints().limit(size).parallel().forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

    /**
     * A parallel unsized stream of longs generates at least 100 values
     */
    public void testUnsizedLongsCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.longs().limit(size).parallel().forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

    /**
     * A parallel unsized stream of doubles generates at least 100 values
     */
    public void testUnsizedDoublesCount() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.doubles().limit(size).parallel().forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

    /**
     * A sequential unsized stream of ints generates at least 100 values
     */
    public void testUnsizedIntsCountSeq() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.ints().limit(size).forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

    /**
     * A sequential unsized stream of longs generates at least 100 values
     */
    public void testUnsizedLongsCountSeq() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.longs().limit(size).forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

    /**
     * A sequential unsized stream of doubles generates at least 100 values
     */
    public void testUnsizedDoublesCountSeq() {
        LongAdder counter = new LongAdder();
        SplittableRandom r = new SplittableRandom();
        long size = 100;
        r.doubles().limit(size).forEach(x -> {counter.increment();});
        assertEquals(counter.sum(), size);
    }

}