ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/jsr166/jsr166/src/test/tck/ThreadLocalRandomTest.java
(Generate patch)

Comparing jsr166/src/test/tck/ThreadLocalRandomTest.java (file contents):
Revision 1.21 by jsr166, Sat Apr 25 04:55:31 2015 UTC vs.
Revision 1.26 by jsr166, Tue Oct 3 22:27:04 2017 UTC

# Line 52 | Line 52 | public class ThreadLocalRandomTest exten
52      }
53  
54      /**
55 +     * 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 +        // Inhibit "An illegal reflective access operation has occurred"
61 +        if (!testImplementationDetails) return;
62 +
63 +        ThreadLocalRandom rnd = ThreadLocalRandom.current();
64 +        final java.lang.reflect.Method m;
65 +        try {
66 +            m = ThreadLocalRandom.class.getDeclaredMethod(
67 +                    "next", new Class[] { int.class });
68 +            m.setAccessible(true);
69 +        } catch (SecurityException acceptable) {
70 +            // Security manager may deny access
71 +            return;
72 +        } catch (Exception ex) {
73 +            // jdk9 module system may deny access
74 +            if (ex.getClass().getSimpleName()
75 +                .equals("InaccessibleObjectException"))
76 +                return;
77 +            throw ex;
78 +        }
79 +
80 +        int i;
81 +        {
82 +            int val = new java.util.Random().nextInt(4);
83 +            for (i = 0; i < NCALLS; i++) {
84 +                int q = (int) m.invoke(rnd, new Object[] { 2 });
85 +                if (val == q) break;
86 +            }
87 +            assertTrue(i < NCALLS);
88 +        }
89 +
90 +        {
91 +            int r = (int) m.invoke(rnd, new Object[] { 3 });
92 +            for (i = 0; i < NCALLS; i++) {
93 +                int q = (int) m.invoke(rnd, new Object[] { 3 });
94 +                assertTrue(q < (1<<3));
95 +                if (r != q) break;
96 +            }
97 +            assertTrue(i < NCALLS);
98 +        }
99 +    }
100 +
101 +    /**
102       * Repeated calls to nextInt produce at least two distinct results
103       */
104      public void testNextInt() {
# Line 338 | Line 385 | public class ThreadLocalRandomTest exten
385          fail("all threads generate the same pseudo-random sequence");
386      }
387  
388 +    /**
389 +     * Repeated calls to nextBytes produce at least values of different signs for every byte
390 +     */
391 +    public void testNextBytes() {
392 +        ThreadLocalRandom rnd = ThreadLocalRandom.current();
393 +        int n = rnd.nextInt(20);
394 +        byte[] bytes = new byte[n];
395 +        outer:
396 +        for (int i = 0; i < n; i++) {
397 +            for (int tries = NCALLS; tries-->0; ) {
398 +                byte before = bytes[i];
399 +                rnd.nextBytes(bytes);
400 +                byte after = bytes[i];
401 +                if (after * before < 0)
402 +                    continue outer;
403 +            }
404 +            fail("not enough variation in random bytes");
405 +        }
406 +    }
407 +
408   }

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines