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From Phil Steitz <>
Subject Re: [math] Re: [GUMP@vmgump]: Project commons-math (in module apache-commons) failed
Date Sun, 24 Jan 2010 20:51:40 GMT
Luc Maisonobe wrote:
> Gump a écrit :
>> To whom it may engage...
>> This is an automated request, but not an unsolicited one. For 
>> more information please visit, 
>> and/or contact the folk at
>> Project commons-math has an issue affecting its community integration.
>> This issue affects 1 projects,
>>  and has been outstanding for 2 runs.
> [snip]
>> /srv/gump/public/workspace/apache-commons/math/build.xml:199: There were test failures.
> The failed test is once again RandomDataTest.testNextPoissonConsistency.
> The output is:
> [junit] Testcase: testNextPoissonConsistency took 0.596 sec
>     [junit] 	FAILED
>     [junit] Chisquare test failed for mean = 2.0 p-value =
> 3.5409049905721357E-4 chisquare statistic = 20.7552099562672.
>     [junit] bin		expected	observed
>     [junit] [1,1)		135.34		165
>     [junit] [1,3)		541.34		572
>     [junit] [3,5)		270.67		226
>     [junit] [5,6)		36.09		23
>     [junit] [6,inf)		16.56		14
>     [junit] This test can fail randomly due to sampling error with
> probability 0.0010.
> I think it is the third time in less than 6 months and the second time
> in row that this test fails, so the 0.001 failure probability seems
> exceeded. IS this related to the comment we find in the test source:
> // TODO: When MATH-282 is resolved, s/3000/10000 below
> Would it be sensible to add some loop around the test and consider it
> fails if 2 or 3 successive iterations all fail ? Would this really test
> something ? Should this test be used only manually during development
> and removed from the suite ?
> I am puzzled by tests that can randomly fail and belong to an automatic
> test suite.

We could disable this test case for now, until MATH-282 is resolved,
but I am not keen on removing it, as (I think) the failures really
are pointing to sickness - which in this case is the Gamma function
issue in MATH-282.  The test case is (most likely [1]) already being
retried twice (RandomDataTest extends RetryTestCase, which retries
tests when it there is a failure); so in fact the probability of
false failure is (probably) (.001)^2.  What is displayed is the
output of the second consecutive failed test.

I am ambivalent on whether or not tests that have small positive
probability of false failure should be included in our unit tests.
I don't personally see it as a big deal if we get a false failure
now and then. If anyone else has a better idea of how to test the
data generation utilities, I am open to changing.  The tests in
there now were certainly useful in development and have flagged some
problems when changing the code, so I would like to at least
maintain something like them.

[1] IIRC, RetryTestCase repeats *all* tests each time *any* test
fails; so it is possible that the first failure is not
testPoissonConsistency.  I think that is unlikely; though, as this
is the only test case that has been reported failing recently.

> Luc
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