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root/jsr166/jsr166/src/test/tck/SplittableRandomTest.java
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Comparing jsr166/src/test/tck/SplittableRandomTest.java (file contents):
Revision 1.21 by jsr166, Thu Nov 17 22:09:52 2016 UTC vs.
Revision 1.22 by jsr166, Tue Oct 3 22:27:04 2017 UTC

# Line 4 | Line 4
4   * http://creativecommons.org/publicdomain/zero/1.0/
5   */
6  
7 + import java.util.Arrays;
8 + import java.util.ArrayList;
9 + import java.util.List;
10   import java.util.SplittableRandom;
11   import java.util.concurrent.atomic.AtomicInteger;
12   import java.util.concurrent.atomic.LongAdder;
13 + import java.lang.reflect.Method;
14 + import java.util.function.Predicate;
15 + import java.util.stream.Collectors;
16  
17   import junit.framework.Test;
18   import junit.framework.TestSuite;
# Line 525 | Line 531 | public class SplittableRandomTest extend
531          assertEquals(size, counter.sum());
532      }
533  
534 +    /**
535 +     * SplittableRandom should implement most of Random's public methods
536 +     */
537 +    public void testShouldImplementMostRandomMethods() throws Throwable {
538 +        Predicate<Method> wasForgotten = method -> {
539 +            String name = method.getName();
540 +            // some methods deliberately not implemented
541 +            if (name.equals("setSeed")) return false;
542 +            if (name.equals("nextFloat")) return false;
543 +            if (name.equals("nextGaussian")) return false;
544 +            try {
545 +                SplittableRandom.class.getMethod(
546 +                    method.getName(), method.getParameterTypes());
547 +            } catch (ReflectiveOperationException ex) {
548 +                return true;
549 +            }
550 +            return false;
551 +        };
552 +        List<Method> forgotten =
553 +            Arrays.stream(java.util.Random.class.getMethods())
554 +            .filter(wasForgotten)
555 +            .collect(Collectors.toList());
556 +        if (!forgotten.isEmpty())
557 +            throw new AssertionError("Please implement: " + forgotten);
558 +    }
559 +
560 +    /**
561 +     * Repeated calls to nextBytes produce at least values of different signs for every byte
562 +     */
563 +    public void testNextBytes() {
564 +        SplittableRandom sr = new SplittableRandom();
565 +        int n = sr.nextInt(20);
566 +        byte[] bytes = new byte[n];
567 +        outer:
568 +        for (int i = 0; i < n; i++) {
569 +            for (int tries = NCALLS; tries-->0; ) {
570 +                byte before = bytes[i];
571 +                sr.nextBytes(bytes);
572 +                byte after = bytes[i];
573 +                if (after * before < 0)
574 +                    continue outer;
575 +            }
576 +            fail("not enough variation in random bytes");
577 +        }
578 +    }
579 +
580   }

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