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https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13395487#comment-13395487
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Dawid Weiss commented on LUCENE-4148:
-------------------------------------
I didn't check _TestUtil, to be honest -- I think it did have a bug with range
overflow passed to nextInt (which is not a problem in practice, but was my
example on how randomized testing can explore unexpected things).
Anyway, as for randomLongBetween -- here you'd need to be more careful about
double's representation so simple scaling won't work (there are ranges of
double that transform to NaNs for example). I am not so strong in numerical
analysis to be able to prove something is a correct solution to the problem. My
(naive) take at this would be to calculate the range and then if split into a
few cases:
1) if it doesn't exceed a positive int, use nextInt()
2) if it doesn't exceed a positive long, use nextLong()
3) if it does exceed positive long, use BigDecimal? :)
Maybe this can be done faster without keeping the uniform distribution
requirement so strong (i.e. use a modulo from a combination of two concatenated
longs as BigDecimal or something like that).
> _TestUtil should be able to generate random longs
> -------------------------------------------------
>
> Key: LUCENE-4148
> URL: https://issues.apache.org/jira/browse/LUCENE-4148
> Project: Lucene - Java
> Issue Type: Improvement
> Components: general/test
> Reporter: Adrien Grand
> Priority: Trivial
>
> It would be helpful in TestPackedInts at least, in order to generate random
> values (as a workaround, we currently generate a random int between 0 and
> {{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
> would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
> -10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
> currently fails because the range of values is {{> Integer.MAX_VALUE}}.
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