test/jdk/java/util/concurrent/tck/ThreadLocalRandomTest.java - platform/libcore - Git at Google

 /*
  * 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.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 /*
  * This file is available under and governed by the GNU General Public
  * License version 2 only, as published by the Free Software Foundation.
  * However, the following notice accompanied the original version of this
  * file:
  *
  * Written by Doug Lea with assistance from members of JCP JSR-166
  * Expert Group and released to the public domain, as explained at
  * http://creativecommons.org/publicdomain/zero/1.0/
  */

 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.AtomicReference;

 import junit.framework.Test;
 import junit.framework.TestSuite;

 public class ThreadLocalRandomTest extends JSR166TestCase {

     public static void main(String[] args) {
         main(suite(), args);
     }
     public static Test suite() {
         return new TestSuite(ThreadLocalRandomTest.class);
     }

     /*
      * Testing coverage notes:
      *
      * We don't test randomness properties, but only that repeated
      * calls, up to NCALLS tries, produce at least one different
      * result.  For bounded versions, we sample various intervals
      * across multiples of primes.
      */

     // 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;

     /**
      * setSeed throws UnsupportedOperationException
      */
     public void testSetSeed() {
         try {
             ThreadLocalRandom.current().setSeed(17);
             shouldThrow();
         } catch (UnsupportedOperationException success) {}
     }

     /**
      * Repeated calls to next (only accessible via reflection) produce
      * at least two distinct results, and repeated calls produce all
      * possible values.
      */
     public void testNext() throws ReflectiveOperationException {
         // Inhibit "An illegal reflective access operation has occurred"
         if (!testImplementationDetails) return;

         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         final java.lang.reflect.Method m;
         try {
             m = ThreadLocalRandom.class.getDeclaredMethod("next", int.class);
             m.setAccessible(true);
         } catch (SecurityException acceptable) {
             // Security manager may deny access
             return;
         } catch (Exception ex) {
             // jdk9 module system may deny access
             if (ex.getClass().getSimpleName()
                 .equals("InaccessibleObjectException"))
                 return;
             throw ex;
         }

         int i;
         {
             int val = new java.util.Random().nextInt(4);
             for (i = 0; i < NCALLS; i++) {
                 int q = (int) m.invoke(rnd, new Object[] { 2 });
                 if (val == q) break;
             }
             assertTrue(i < NCALLS);
         }

         {
             int r = (int) m.invoke(rnd, new Object[] { 3 });
             for (i = 0; i < NCALLS; i++) {
                 int q = (int) m.invoke(rnd, new Object[] { 3 });
                 assertTrue(q < (1<<3));
                 if (r != q) break;
             }
             assertTrue(i < NCALLS);
         }
     }

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

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

     /**
      * Repeated calls to nextBoolean produce at least two distinct results
      */
     public void testNextBoolean() {
         boolean f = ThreadLocalRandom.current().nextBoolean();
         int i = 0;
         while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
             ++i;
         assertTrue(i < NCALLS);
     }

     /**
      * Repeated calls to nextFloat produce at least two distinct results
      */
     public void testNextFloat() {
         float f = ThreadLocalRandom.current().nextFloat();
         int i = 0;
         while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
             ++i;
         assertTrue(i < NCALLS);
     }

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

     /**
      * Repeated calls to nextGaussian produce at least two distinct results
      */
     public void testNextGaussian() {
         double f = ThreadLocalRandom.current().nextGaussian();
         int i = 0;
         while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
             ++i;
         assertTrue(i < NCALLS);
     }

     /**
      * nextInt(non-positive) throws IllegalArgumentException
      */
     public void testNextIntBoundNonPositive() {
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
             try {
                 rnd.nextInt(bound);
                 shouldThrow();
             } catch (IllegalArgumentException success) {}
         }
     }

     /**
      * nextInt(least >= bound) throws IllegalArgumentException
      */
     public void testNextIntBadBounds() {
         int[][] badBoundss = {
             { 17, 2 },
             { -42, -42 },
             { Integer.MAX_VALUE, Integer.MIN_VALUE },
         };
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         for (int[] badBounds : badBoundss) {
             try {
                 rnd.nextInt(badBounds[0], badBounds[1]);
                 shouldThrow();
             } catch (IllegalArgumentException success) {}
         }
     }

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

     /**
      * nextLong(non-positive) throws IllegalArgumentException
      */
     public void testNextLongBoundNonPositive() {
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
             try {
                 rnd.nextLong(bound);
                 shouldThrow();
             } catch (IllegalArgumentException success) {}
         }
     }

     /**
      * nextLong(least >= bound) throws IllegalArgumentException
      */
     public void testNextLongBadBounds() {
         long[][] badBoundss = {
             { 17L, 2L },
             { -42L, -42L },
             { Long.MAX_VALUE, Long.MIN_VALUE },
         };
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         for (long[] badBounds : badBoundss) {
             try {
                 rnd.nextLong(badBounds[0], badBounds[1]);
                 shouldThrow();
             } catch (IllegalArgumentException success) {}
         }
     }

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

     /**
      * nextDouble(non-positive) throws IllegalArgumentException
      */
     public void testNextDoubleBoundNonPositive() {
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         double[] badBounds = {
             0.0d,
             -17.0d,
             -Double.MIN_VALUE,
             Double.NEGATIVE_INFINITY,
             Double.NaN,
         };
         for (double bound : badBounds) {
             try {
                 rnd.nextDouble(bound);
                 shouldThrow();
             } catch (IllegalArgumentException success) {}
         }
     }

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

     /**
      * Different threads produce different pseudo-random sequences
      */
     public void testDifferentSequences() {
         // Don't use main thread's ThreadLocalRandom - it is likely to
         // be polluted by previous tests.
         final AtomicReference<ThreadLocalRandom> threadLocalRandom =
             new AtomicReference<>();
         final AtomicLong rand = new AtomicLong();

         long firstRand = 0;
         ThreadLocalRandom firstThreadLocalRandom = null;

         Runnable getRandomState = new CheckedRunnable() {
             public void realRun() {
                 ThreadLocalRandom current = ThreadLocalRandom.current();
                 assertSame(current, ThreadLocalRandom.current());
                 // test bug: the following is not guaranteed and not true in JDK8
                 //                assertNotSame(current, threadLocalRandom.get());
                 rand.set(current.nextLong());
                 threadLocalRandom.set(current);
             }};

         Thread first = newStartedThread(getRandomState);
         awaitTermination(first);
         firstRand = rand.get();
         firstThreadLocalRandom = threadLocalRandom.get();

         for (int i = 0; i < NCALLS; i++) {
             Thread t = newStartedThread(getRandomState);
             awaitTermination(t);
             if (firstRand != rand.get())
                 return;
         }
         fail("all threads generate the same pseudo-random sequence");
     }

     /**
      * Repeated calls to nextBytes produce at least values of different signs for every byte
      */
     public void testNextBytes() {
         ThreadLocalRandom rnd = ThreadLocalRandom.current();
         int n = rnd.nextInt(1, 20);
         byte[] bytes = new byte[n];
         outer:
         for (int i = 0; i < n; i++) {
             for (int tries = NCALLS; tries-->0; ) {
                 byte before = bytes[i];
                 rnd.nextBytes(bytes);
                 byte after = bytes[i];
                 if (after * before < 0)
                     continue outer;
             }
             fail("not enough variation in random bytes");
         }
     }

     /**
      * Filling an empty array with random bytes succeeds without effect.
      */
     public void testNextBytes_emptyArray() {
         ThreadLocalRandom.current().nextBytes(new byte[0]);
     }

     public void testNextBytes_nullArray() {
         try {
             ThreadLocalRandom.current().nextBytes(null);
             shouldThrow();
         } catch (NullPointerException success) {}
     }

 }
	/*
	* 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.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	/*
	* This file is available under and governed by the GNU General Public
	* License version 2 only, as published by the Free Software Foundation.
	* However, the following notice accompanied the original version of this
	* file:
	*
	* Written by Doug Lea with assistance from members of JCP JSR-166
	* Expert Group and released to the public domain, as explained at
	* http://creativecommons.org/publicdomain/zero/1.0/
	*/

	import java.util.concurrent.ThreadLocalRandom;
	import java.util.concurrent.atomic.AtomicLong;
	import java.util.concurrent.atomic.AtomicReference;

	import junit.framework.Test;
	import junit.framework.TestSuite;

	public class ThreadLocalRandomTest extends JSR166TestCase {

	public static void main(String[] args) {
	main(suite(), args);
	}
	public static Test suite() {
	return new TestSuite(ThreadLocalRandomTest.class);
	}

	/*
	* Testing coverage notes:
	*
	* We don't test randomness properties, but only that repeated
	* calls, up to NCALLS tries, produce at least one different
	* result. For bounded versions, we sample various intervals
	* across multiples of primes.
	*/

	// 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;

	/**
	* setSeed throws UnsupportedOperationException
	*/
	public void testSetSeed() {
	try {
	ThreadLocalRandom.current().setSeed(17);
	shouldThrow();
	} catch (UnsupportedOperationException success) {}
	}

	/**
	* Repeated calls to next (only accessible via reflection) produce
	* at least two distinct results, and repeated calls produce all
	* possible values.
	*/
	public void testNext() throws ReflectiveOperationException {
	// Inhibit "An illegal reflective access operation has occurred"
	if (!testImplementationDetails) return;

	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	final java.lang.reflect.Method m;
	try {
	m = ThreadLocalRandom.class.getDeclaredMethod("next", int.class);
	m.setAccessible(true);
	} catch (SecurityException acceptable) {
	// Security manager may deny access
	return;
	} catch (Exception ex) {
	// jdk9 module system may deny access
	if (ex.getClass().getSimpleName()
	.equals("InaccessibleObjectException"))
	return;
	throw ex;
	}

	int i;
	{
	int val = new java.util.Random().nextInt(4);
	for (i = 0; i < NCALLS; i++) {
	int q = (int) m.invoke(rnd, new Object[] { 2 });
	if (val == q) break;
	}
	assertTrue(i < NCALLS);
	}

	{
	int r = (int) m.invoke(rnd, new Object[] { 3 });
	for (i = 0; i < NCALLS; i++) {
	int q = (int) m.invoke(rnd, new Object[] { 3 });
	assertTrue(q < (1<<3));
	if (r != q) break;
	}
	assertTrue(i < NCALLS);
	}
	}

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

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

	/**
	* Repeated calls to nextBoolean produce at least two distinct results
	*/
	public void testNextBoolean() {
	boolean f = ThreadLocalRandom.current().nextBoolean();
	int i = 0;
	while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
	++i;
	assertTrue(i < NCALLS);
	}

	/**
	* Repeated calls to nextFloat produce at least two distinct results
	*/
	public void testNextFloat() {
	float f = ThreadLocalRandom.current().nextFloat();
	int i = 0;
	while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
	++i;
	assertTrue(i < NCALLS);
	}

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

	/**
	* Repeated calls to nextGaussian produce at least two distinct results
	*/
	public void testNextGaussian() {
	double f = ThreadLocalRandom.current().nextGaussian();
	int i = 0;
	while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
	++i;
	assertTrue(i < NCALLS);
	}

	/**
	* nextInt(non-positive) throws IllegalArgumentException
	*/
	public void testNextIntBoundNonPositive() {
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
	try {
	rnd.nextInt(bound);
	shouldThrow();
	} catch (IllegalArgumentException success) {}
	}
	}

	/**
	* nextInt(least >= bound) throws IllegalArgumentException
	*/
	public void testNextIntBadBounds() {
	int[][] badBoundss = {
	{ 17, 2 },
	{ -42, -42 },
	{ Integer.MAX_VALUE, Integer.MIN_VALUE },
	};
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	for (int[] badBounds : badBoundss) {
	try {
	rnd.nextInt(badBounds[0], badBounds[1]);
	shouldThrow();
	} catch (IllegalArgumentException success) {}
	}
	}

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

	/**
	* nextLong(non-positive) throws IllegalArgumentException
	*/
	public void testNextLongBoundNonPositive() {
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
	try {
	rnd.nextLong(bound);
	shouldThrow();
	} catch (IllegalArgumentException success) {}
	}
	}

	/**
	* nextLong(least >= bound) throws IllegalArgumentException
	*/
	public void testNextLongBadBounds() {
	long[][] badBoundss = {
	{ 17L, 2L },
	{ -42L, -42L },
	{ Long.MAX_VALUE, Long.MIN_VALUE },
	};
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	for (long[] badBounds : badBoundss) {
	try {
	rnd.nextLong(badBounds[0], badBounds[1]);
	shouldThrow();
	} catch (IllegalArgumentException success) {}
	}
	}

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

	/**
	* nextDouble(non-positive) throws IllegalArgumentException
	*/
	public void testNextDoubleBoundNonPositive() {
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	double[] badBounds = {
	0.0d,
	-17.0d,
	-Double.MIN_VALUE,
	Double.NEGATIVE_INFINITY,
	Double.NaN,
	};
	for (double bound : badBounds) {
	try {
	rnd.nextDouble(bound);
	shouldThrow();
	} catch (IllegalArgumentException success) {}
	}
	}

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

	/**
	* Different threads produce different pseudo-random sequences
	*/
	public void testDifferentSequences() {
	// Don't use main thread's ThreadLocalRandom - it is likely to
	// be polluted by previous tests.
	final AtomicReference<ThreadLocalRandom> threadLocalRandom =
	new AtomicReference<>();
	final AtomicLong rand = new AtomicLong();

	long firstRand = 0;
	ThreadLocalRandom firstThreadLocalRandom = null;

	Runnable getRandomState = new CheckedRunnable() {
	public void realRun() {
	ThreadLocalRandom current = ThreadLocalRandom.current();
	assertSame(current, ThreadLocalRandom.current());
	// test bug: the following is not guaranteed and not true in JDK8
	// assertNotSame(current, threadLocalRandom.get());
	rand.set(current.nextLong());
	threadLocalRandom.set(current);
	}};

	Thread first = newStartedThread(getRandomState);
	awaitTermination(first);
	firstRand = rand.get();
	firstThreadLocalRandom = threadLocalRandom.get();

	for (int i = 0; i < NCALLS; i++) {
	Thread t = newStartedThread(getRandomState);
	awaitTermination(t);
	if (firstRand != rand.get())
	return;
	}
	fail("all threads generate the same pseudo-random sequence");
	}

	/**
	* Repeated calls to nextBytes produce at least values of different signs for every byte
	*/
	public void testNextBytes() {
	ThreadLocalRandom rnd = ThreadLocalRandom.current();
	int n = rnd.nextInt(1, 20);
	byte[] bytes = new byte[n];
	outer:
	for (int i = 0; i < n; i++) {
	for (int tries = NCALLS; tries-->0; ) {
	byte before = bytes[i];
	rnd.nextBytes(bytes);
	byte after = bytes[i];
	if (after * before < 0)
	continue outer;
	}
	fail("not enough variation in random bytes");
	}
	}

	/**
	* Filling an empty array with random bytes succeeds without effect.
	*/
	public void testNextBytes_emptyArray() {
	ThreadLocalRandom.current().nextBytes(new byte[0]);
	}

	public void testNextBytes_nullArray() {
	try {
	ThreadLocalRandom.current().nextBytes(null);
	shouldThrow();
	} catch (NullPointerException success) {}
	}

	}