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Make tst_QRandomGenerator::qualityReal() test more stable

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Increasing the sample size of randomly generated test samples reduces
the probability of small deviations from the expected uniform
distribution.

On my machine with the new values the test fails approximately once per
3000 consecutive runs, instead of failing once per 300.

Change-Id: I4d1815504c353290a2fb350b3fd1cbb802f8d559
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Sona Kurazyan 2020-03-17 16:40:34 +01:00
parent 028ddf3633
commit f22c929c8a
1 changed files with 3 additions and 3 deletions
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6
tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp
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@ -671,7 +671,7 @@ void tst_QRandomGenerator::qualityReal()
RandomGenerator rng(control);
enum {
SampleSize = 160,
SampleSize = 16000,
// Expected value: sample size times proportion of the range:
PerfectOctile = SampleSize / 8,
@ -679,8 +679,8 @@ void tst_QRandomGenerator::qualityReal()
// Variance is (1 - proportion of range) * expected; sqrt() for standard deviations.
// Should usually be within twice that and almost never outside four times:
RangeHalf = 25, // floor(4 * sqrt((1 - 0.5) * PerfectHalf))
RangeOctile = 16 // floor(4 * sqrt((1 - 0.125) * PerfectOctile))
RangeHalf = 252, // floor(4 * sqrt((1 - 0.5) * PerfectHalf))
RangeOctile = 167 // floor(4 * sqrt((1 - 0.125) * PerfectOctile))
};
double data[SampleSize];