--- jsr166/src/test/tck/ThreadLocalRandomTest.java	2016/11/13 03:36:50	1.22
+++ jsr166/src/test/tck/ThreadLocalRandomTest.java	2018/01/28 16:41:13	1.29
@@ -57,33 +57,44 @@ public class ThreadLocalRandomTest exten
      * 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 {
-            java.lang.reflect.Method m
-                = ThreadLocalRandom.class.getDeclaredMethod(
-                    "next", new Class[] { int.class });
+            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 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);
+        {
+            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;
             }
-        } catch (SecurityException acceptable) {}
+            assertTrue(i < NCALLS);
+        }
     }
 
     /**
@@ -343,7 +354,7 @@ public class ThreadLocalRandomTest exten
         // Don't use main thread's ThreadLocalRandom - it is likely to
         // be polluted by previous tests.
         final AtomicReference<ThreadLocalRandom> threadLocalRandom =
-            new AtomicReference<ThreadLocalRandom>();
+            new AtomicReference<>();
         final AtomicLong rand = new AtomicLong();
 
         long firstRand = 0;
@@ -373,4 +384,38 @@ public class ThreadLocalRandomTest exten
         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) {}
+    }
+
 }