diff options
Diffstat (limited to 'tests')
-rw-r--r-- | tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp b/tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp index 2195bf8ec8..d1c0c8e965 100644 --- a/tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp +++ b/tests/auto/corelib/global/qrandomgenerator/tst_qrandomgenerator.cpp @@ -97,6 +97,8 @@ private slots: void generateReal_data() { generate32_data(); } void generateReal(); + void qualityReal_data() { generate32_data(); } + void qualityReal(); void seedStdRandomEngines(); void stdUniformIntDistribution_data(); @@ -445,7 +447,7 @@ void tst_QRandomGenerator::generateReal() for (int i = 0; i < 4; ++i) { QVERIFY_3TIMES([] { qreal value = QRandomGenerator::generateDouble(); - return value > 0 && value < 1 && value != RandomValueFP; + return value >= 0 && value < 1 && value != RandomValueFP; }()); } @@ -454,6 +456,52 @@ void tst_QRandomGenerator::generateReal() QVERIFY_3TIMES(QRandomGenerator::generateDouble() != QRandomGenerator::generateDouble()); } +void tst_QRandomGenerator::qualityReal() +{ + QFETCH(uint, control); + setRNGControl(control); + + enum { + SampleSize = 160, + + // Expected value: sample size times proportion of the range: + PerfectOctile = SampleSize / 8, + PerfectHalf = SampleSize / 2, + + // 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)) + }; + + double data[SampleSize]; + std::generate(std::begin(data), std::end(data), &QRandomGenerator::generateDouble); + + int aboveHalf = 0; + int belowOneEighth = 0; + int aboveSevenEighths = 0; + for (double x : data) { + aboveHalf += x >= 0.5; + belowOneEighth += x < 0.125; + aboveSevenEighths += x >= 0.875; + + // these are strict requirements + QVERIFY(x >= 0); + QVERIFY(x < 1); + } + + qInfo("Halfway distribution: %.1f - %.1f", 100. * aboveHalf / SampleSize, 100 - 100. * aboveHalf / SampleSize); + qInfo("%.1f below 1/8 (expected 12.5%% ideally)", 100. * belowOneEighth / SampleSize); + qInfo("%.1f above 7/8 (expected 12.5%% ideally)", 100. * aboveSevenEighths / SampleSize); + + QVERIFY(aboveHalf < PerfectHalf + RangeHalf); + QVERIFY(aboveHalf > PerfectHalf - RangeHalf); + QVERIFY(aboveSevenEighths < PerfectOctile + RangeOctile); + QVERIFY(aboveSevenEighths > PerfectOctile - RangeOctile); + QVERIFY(belowOneEighth < PerfectOctile + RangeOctile); + QVERIFY(belowOneEighth > PerfectOctile - RangeOctile); +} + template <typename Engine> void seedStdRandomEngine() { QRandomGenerator rd; |