test/tck/ThreadLocalRandomTest.java

/*
 * 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();

        Runnable getRandomState = new CheckedRunnable() {
            public void realRun() {
                ThreadLocalRandom current = ThreadLocalRandom.current();
                assertSame(current, ThreadLocalRandom.current());
                rand.set(current.nextLong());
                threadLocalRandom.set(current);
            }};

        awaitTermination(newStartedThread(getRandomState));
        long firstRand = rand.get();
        ThreadLocalRandom firstThreadLocalRandom = threadLocalRandom.get();
        assertNotNull(firstThreadLocalRandom);

        for (int i = 0; i < NCALLS; i++) {
            awaitTermination(newStartedThread(getRandomState));
            if (testImplementationDetails)
                // ThreadLocalRandom has been a singleton since jdk8.
                assertSame(firstThreadLocalRandom, threadLocalRandom.get());
            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) {}
    }

}
Revision:	1.30
Committed:	Wed Aug 12 17:39:43 2020 UTC (3 years, 9 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.29:	+8 -11 lines
Log Message:	testDifferentSequences: cleaner
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4	jsr166	1.8	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6	jsr166	1.20
7	jsr166	1.10	import java.util.concurrent.ThreadLocalRandom;
8	jsr166	1.11	import java.util.concurrent.atomic.AtomicLong;
9			import java.util.concurrent.atomic.AtomicReference;
10	dl	1.1
11	jsr166	1.20	import junit.framework.Test;
12			import junit.framework.TestSuite;
13
14	dl	1.1	public class ThreadLocalRandomTest extends JSR166TestCase {
15
16			public static void main(String[] args) {
17	jsr166	1.21	main(suite(), args);
18	dl	1.1	}
19			public static Test suite() {
20	jsr166	1.4	return new TestSuite(ThreadLocalRandomTest.class);
21	dl	1.1	}
22
23	jsr166	1.13	/*
24	dl	1.1	* Testing coverage notes:
25	jsr166	1.2	*
26	dl	1.1	* We don't test randomness properties, but only that repeated
27			* calls, up to NCALLS tries, produce at least one different
28			* result. For bounded versions, we sample various intervals
29			* across multiples of primes.
30			*/
31
32	jsr166	1.14	// max numbers of calls to detect getting stuck on one value
33	dl	1.1	static final int NCALLS = 10000;
34
35			// max sampled int bound
36			static final int MAX_INT_BOUND = (1 << 28);
37
38	jsr166	1.14	// max sampled long bound
39	dl	1.1	static final long MAX_LONG_BOUND = (1L << 42);
40
41	dl	1.15	// Number of replications for other checks
42			static final int REPS = 20;
43
44	dl	1.1	/**
45			* setSeed throws UnsupportedOperationException
46			*/
47			public void testSetSeed() {
48			try {
49			ThreadLocalRandom.current().setSeed(17);
50	jsr166	1.3	shouldThrow();
51	jsr166	1.5	} catch (UnsupportedOperationException success) {}
52	dl	1.1	}
53
54			/**
55	jsr166	1.22	* Repeated calls to next (only accessible via reflection) produce
56			* at least two distinct results, and repeated calls produce all
57			* possible values.
58			*/
59			public void testNext() throws ReflectiveOperationException {
60	jsr166	1.25	// Inhibit "An illegal reflective access operation has occurred"
61			if (!testImplementationDetails) return;
62
63	jsr166	1.22	ThreadLocalRandom rnd = ThreadLocalRandom.current();
64	jsr166	1.23	final java.lang.reflect.Method m;
65	jsr166	1.22	try {
66	jsr166	1.29	m = ThreadLocalRandom.class.getDeclaredMethod("next", int.class);
67	jsr166	1.22	m.setAccessible(true);
68	jsr166	1.24	} catch (SecurityException acceptable) {
69			// Security manager may deny access
70	jsr166	1.23	return;
71	jsr166	1.24	} catch (Exception ex) {
72			// jdk9 module system may deny access
73			if (ex.getClass().getSimpleName()
74			.equals("InaccessibleObjectException"))
75			return;
76			throw ex;
77	jsr166	1.23	}
78	jsr166	1.22
79	jsr166	1.23	int i;
80			{
81			int val = new java.util.Random().nextInt(4);
82			for (i = 0; i < NCALLS; i++) {
83			int q = (int) m.invoke(rnd, new Object[] { 2 });
84			if (val == q) break;
85	jsr166	1.22	}
86	jsr166	1.23	assertTrue(i < NCALLS);
87			}
88	jsr166	1.22
89	jsr166	1.23	{
90			int r = (int) m.invoke(rnd, new Object[] { 3 });
91			for (i = 0; i < NCALLS; i++) {
92			int q = (int) m.invoke(rnd, new Object[] { 3 });
93			assertTrue(q < (1<<3));
94			if (r != q) break;
95	jsr166	1.22	}
96	jsr166	1.23	assertTrue(i < NCALLS);
97			}
98	jsr166	1.22	}
99
100			/**
101	jsr166	1.14	* Repeated calls to nextInt produce at least two distinct results
102	dl	1.1	*/
103			public void testNextInt() {
104			int f = ThreadLocalRandom.current().nextInt();
105			int i = 0;
106			while (i < NCALLS && ThreadLocalRandom.current().nextInt() == f)
107			++i;
108			assertTrue(i < NCALLS);
109			}
110
111			/**
112	jsr166	1.14	* Repeated calls to nextLong produce at least two distinct results
113	dl	1.1	*/
114			public void testNextLong() {
115			long f = ThreadLocalRandom.current().nextLong();
116			int i = 0;
117			while (i < NCALLS && ThreadLocalRandom.current().nextLong() == f)
118			++i;
119			assertTrue(i < NCALLS);
120			}
121
122			/**
123	jsr166	1.14	* Repeated calls to nextBoolean produce at least two distinct results
124	dl	1.1	*/
125			public void testNextBoolean() {
126			boolean f = ThreadLocalRandom.current().nextBoolean();
127			int i = 0;
128			while (i < NCALLS && ThreadLocalRandom.current().nextBoolean() == f)
129			++i;
130			assertTrue(i < NCALLS);
131			}
132
133			/**
134	jsr166	1.14	* Repeated calls to nextFloat produce at least two distinct results
135	dl	1.1	*/
136			public void testNextFloat() {
137			float f = ThreadLocalRandom.current().nextFloat();
138			int i = 0;
139			while (i < NCALLS && ThreadLocalRandom.current().nextFloat() == f)
140			++i;
141			assertTrue(i < NCALLS);
142			}
143
144			/**
145	jsr166	1.14	* Repeated calls to nextDouble produce at least two distinct results
146	dl	1.1	*/
147			public void testNextDouble() {
148			double f = ThreadLocalRandom.current().nextDouble();
149	jsr166	1.14	int i = 0;
150	dl	1.1	while (i < NCALLS && ThreadLocalRandom.current().nextDouble() == f)
151			++i;
152			assertTrue(i < NCALLS);
153			}
154
155			/**
156	jsr166	1.14	* Repeated calls to nextGaussian produce at least two distinct results
157	dl	1.1	*/
158			public void testNextGaussian() {
159			double f = ThreadLocalRandom.current().nextGaussian();
160			int i = 0;
161			while (i < NCALLS && ThreadLocalRandom.current().nextGaussian() == f)
162			++i;
163			assertTrue(i < NCALLS);
164			}
165
166			/**
167	jsr166	1.19	* nextInt(non-positive) throws IllegalArgumentException
168	dl	1.1	*/
169	jsr166	1.19	public void testNextIntBoundNonPositive() {
170			ThreadLocalRandom rnd = ThreadLocalRandom.current();
171			for (int bound : new int[] { 0, -17, Integer.MIN_VALUE }) {
172			try {
173			rnd.nextInt(bound);
174			shouldThrow();
175			} catch (IllegalArgumentException success) {}
176			}
177	dl	1.1	}
178
179			/**
180	jsr166	1.14	* nextInt(least >= bound) throws IllegalArgumentException
181	dl	1.1	*/
182			public void testNextIntBadBounds() {
183	jsr166	1.19	int[][] badBoundss = {
184			{ 17, 2 },
185			{ -42, -42 },
186			{ Integer.MAX_VALUE, Integer.MIN_VALUE },
187			};
188			ThreadLocalRandom rnd = ThreadLocalRandom.current();
189			for (int[] badBounds : badBoundss) {
190			try {
191			rnd.nextInt(badBounds[0], badBounds[1]);
192			shouldThrow();
193			} catch (IllegalArgumentException success) {}
194			}
195	dl	1.1	}
196
197			/**
198			* nextInt(bound) returns 0 <= value < bound;
199	jsr166	1.14	* repeated calls produce at least two distinct results
200	dl	1.1	*/
201			public void testNextIntBounded() {
202			// sample bound space across prime number increments
203			for (int bound = 2; bound < MAX_INT_BOUND; bound += 524959) {
204			int f = ThreadLocalRandom.current().nextInt(bound);
205			assertTrue(0 <= f && f < bound);
206			int i = 0;
207			int j;
208	jsr166	1.2	while (i < NCALLS &&
209	dl	1.1	(j = ThreadLocalRandom.current().nextInt(bound)) == f) {
210			assertTrue(0 <= j && j < bound);
211			++i;
212			}
213			assertTrue(i < NCALLS);
214			}
215			}
216
217			/**
218			* nextInt(least, bound) returns least <= value < bound;
219	jsr166	1.14	* repeated calls produce at least two distinct results
220	dl	1.1	*/
221			public void testNextIntBounded2() {
222			for (int least = -15485863; least < MAX_INT_BOUND; least += 524959) {
223			for (int bound = least + 2; bound > least && bound < MAX_INT_BOUND; bound += 49979687) {
224			int f = ThreadLocalRandom.current().nextInt(least, bound);
225			assertTrue(least <= f && f < bound);
226			int i = 0;
227			int j;
228	jsr166	1.2	while (i < NCALLS &&
229	dl	1.1	(j = ThreadLocalRandom.current().nextInt(least, bound)) == f) {
230			assertTrue(least <= j && j < bound);
231			++i;
232			}
233			assertTrue(i < NCALLS);
234			}
235			}
236			}
237
238			/**
239	jsr166	1.19	* nextLong(non-positive) throws IllegalArgumentException
240	dl	1.1	*/
241	jsr166	1.19	public void testNextLongBoundNonPositive() {
242			ThreadLocalRandom rnd = ThreadLocalRandom.current();
243			for (long bound : new long[] { 0L, -17L, Long.MIN_VALUE }) {
244			try {
245			rnd.nextLong(bound);
246			shouldThrow();
247			} catch (IllegalArgumentException success) {}
248			}
249	dl	1.1	}
250
251			/**
252	jsr166	1.14	* nextLong(least >= bound) throws IllegalArgumentException
253	dl	1.1	*/
254			public void testNextLongBadBounds() {
255	jsr166	1.19	long[][] badBoundss = {
256			{ 17L, 2L },
257			{ -42L, -42L },
258			{ Long.MAX_VALUE, Long.MIN_VALUE },
259			};
260			ThreadLocalRandom rnd = ThreadLocalRandom.current();
261			for (long[] badBounds : badBoundss) {
262			try {
263			rnd.nextLong(badBounds[0], badBounds[1]);
264			shouldThrow();
265			} catch (IllegalArgumentException success) {}
266			}
267	dl	1.1	}
268
269			/**
270			* nextLong(bound) returns 0 <= value < bound;
271	jsr166	1.14	* repeated calls produce at least two distinct results
272	dl	1.1	*/
273			public void testNextLongBounded() {
274			for (long bound = 2; bound < MAX_LONG_BOUND; bound += 15485863) {
275			long f = ThreadLocalRandom.current().nextLong(bound);
276			assertTrue(0 <= f && f < bound);
277			int i = 0;
278			long j;
279	jsr166	1.2	while (i < NCALLS &&
280	dl	1.1	(j = ThreadLocalRandom.current().nextLong(bound)) == f) {
281			assertTrue(0 <= j && j < bound);
282			++i;
283			}
284			assertTrue(i < NCALLS);
285			}
286			}
287
288			/**
289			* nextLong(least, bound) returns least <= value < bound;
290	jsr166	1.14	* repeated calls produce at least two distinct results
291	dl	1.1	*/
292			public void testNextLongBounded2() {
293			for (long least = -86028121; least < MAX_LONG_BOUND; least += 982451653L) {
294			for (long bound = least + 2; bound > least && bound < MAX_LONG_BOUND; bound += Math.abs(bound * 7919)) {
295			long f = ThreadLocalRandom.current().nextLong(least, bound);
296			assertTrue(least <= f && f < bound);
297			int i = 0;
298			long j;
299	jsr166	1.2	while (i < NCALLS &&
300	dl	1.1	(j = ThreadLocalRandom.current().nextLong(least, bound)) == f) {
301			assertTrue(least <= j && j < bound);
302			++i;
303			}
304			assertTrue(i < NCALLS);
305			}
306			}
307			}
308
309			/**
310	jsr166	1.19	* nextDouble(non-positive) throws IllegalArgumentException
311			*/
312			public void testNextDoubleBoundNonPositive() {
313			ThreadLocalRandom rnd = ThreadLocalRandom.current();
314			double[] badBounds = {
315			0.0d,
316			-17.0d,
317			-Double.MIN_VALUE,
318			Double.NEGATIVE_INFINITY,
319			Double.NaN,
320			};
321			for (double bound : badBounds) {
322			try {
323			rnd.nextDouble(bound);
324			shouldThrow();
325			} catch (IllegalArgumentException success) {}
326			}
327			}
328
329			/**
330	dl	1.1	* nextDouble(least, bound) returns least <= value < bound;
331	jsr166	1.14	* repeated calls produce at least two distinct results
332	dl	1.1	*/
333			public void testNextDoubleBounded2() {
334			for (double least = 0.0001; least < 1.0e20; least *= 8) {
335			for (double bound = least * 1.001; bound < 1.0e20; bound *= 16) {
336			double f = ThreadLocalRandom.current().nextDouble(least, bound);
337			assertTrue(least <= f && f < bound);
338			int i = 0;
339			double j;
340	jsr166	1.2	while (i < NCALLS &&
341	dl	1.1	(j = ThreadLocalRandom.current().nextDouble(least, bound)) == f) {
342			assertTrue(least <= j && j < bound);
343			++i;
344			}
345			assertTrue(i < NCALLS);
346			}
347			}
348			}
349
350	jsr166	1.11	/**
351			* Different threads produce different pseudo-random sequences
352			*/
353			public void testDifferentSequences() {
354			// Don't use main thread's ThreadLocalRandom - it is likely to
355			// be polluted by previous tests.
356			final AtomicReference<ThreadLocalRandom> threadLocalRandom =
357	jsr166	1.28	new AtomicReference<>();
358	jsr166	1.11	final AtomicLong rand = new AtomicLong();
359
360	jsr166	1.18	Runnable getRandomState = new CheckedRunnable() {
361	jsr166	1.11	public void realRun() {
362			ThreadLocalRandom current = ThreadLocalRandom.current();
363			assertSame(current, ThreadLocalRandom.current());
364			rand.set(current.nextLong());
365			threadLocalRandom.set(current);
366			}};
367
368	jsr166	1.30	awaitTermination(newStartedThread(getRandomState));
369			long firstRand = rand.get();
370			ThreadLocalRandom firstThreadLocalRandom = threadLocalRandom.get();
371			assertNotNull(firstThreadLocalRandom);
372	jsr166	1.11
373			for (int i = 0; i < NCALLS; i++) {
374	jsr166	1.30	awaitTermination(newStartedThread(getRandomState));
375			if (testImplementationDetails)
376			// ThreadLocalRandom has been a singleton since jdk8.
377			assertSame(firstThreadLocalRandom, threadLocalRandom.get());
378	jsr166	1.11	if (firstRand != rand.get())
379			return;
380			}
381			fail("all threads generate the same pseudo-random sequence");
382			}
383
384	jsr166	1.26	/**
385			* Repeated calls to nextBytes produce at least values of different signs for every byte
386			*/
387			public void testNextBytes() {
388			ThreadLocalRandom rnd = ThreadLocalRandom.current();
389	jsr166	1.27	int n = rnd.nextInt(1, 20);
390	jsr166	1.26	byte[] bytes = new byte[n];
391			outer:
392			for (int i = 0; i < n; i++) {
393			for (int tries = NCALLS; tries-->0; ) {
394			byte before = bytes[i];
395			rnd.nextBytes(bytes);
396			byte after = bytes[i];
397			if (after * before < 0)
398			continue outer;
399			}
400			fail("not enough variation in random bytes");
401			}
402			}
403
404	jsr166	1.27	/**
405			* Filling an empty array with random bytes succeeds without effect.
406			*/
407			public void testNextBytes_emptyArray() {
408			ThreadLocalRandom.current().nextBytes(new byte[0]);
409			}
410
411			public void testNextBytes_nullArray() {
412			try {
413			ThreadLocalRandom.current().nextBytes(null);
414			shouldThrow();
415			} catch (NullPointerException success) {}
416			}
417
418	dl	1.1	}