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Fix flaky QElapsedTimer::elapsed test case

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Much of this test case was testing that the machine it runs on didn't
take more than an expected amount of time, which is an assumption that
won't hold in a virtual environment where the hypervisor might decide
to not allocate any CPU time to the machine at certain times.

Instead, take the samples that we want to compare with once, then
use them as reference for further comparisons.

Also, split the test in two, with the comparison operators and msecsTo
test moved into a separate test function.

Change-Id: I7db12b8e02552f4d63af933c1b0fee9d62b591eb
Fixes: QTBUG-58713
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Volker Hilsheimer 2020-02-27 09:53:49 +01:00
parent 529cfe4e22
commit 715468df40
1 changed files with 30 additions and 17 deletions
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47
tests/auto/corelib/kernel/qelapsedtimer/tst_qelapsedtimer.cpp
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@ -48,6 +48,7 @@ private Q_SLOTS:
void validity();
void basics();
void elapsed();
void msecsTo();
};
void tst_QElapsedTimer::statics()
@ -108,30 +109,42 @@ void tst_QElapsedTimer::elapsed()
t1.start();
QTest::qSleep(2*minResolution);
auto nsecs = t1.nsecsElapsed();
auto msecs = t1.elapsed();
QVERIFY(nsecs > 0);
QVERIFY(msecs > 0);
// the number of elapsed nanoseconds and milliseconds should match
QVERIFY(nsecs - msecs * 1000000 < 1000000);
if (msecs > 8 * minResolution)
QSKIP("Sampling timer took too long, aborting test");
QVERIFY(t1.hasExpired(minResolution));
QVERIFY(!t1.hasExpired(8*minResolution));
QVERIFY(!t1.hasExpired(-1));
qint64 elapsed = t1.restart();
QVERIFY(elapsed >= msecs);
QVERIFY(elapsed < msecs + 3*minResolution);
}
void tst_QElapsedTimer::msecsTo()
{
QElapsedTimer t1;
t1.start();
QTest::qSleep(minResolution);
QElapsedTimer t2;
t2.start();
QVERIFY(t1 != t2);
QVERIFY(!(t1 == t2));
QVERIFY(t1 < t2);
QVERIFY(t1.msecsTo(t2) > 0);
QVERIFY(t1.nsecsElapsed() > 0);
QVERIFY(t1.elapsed() > 0);
// the number of elapsed nanoseconds and milliseconds should match
QVERIFY(t1.nsecsElapsed() - t1.elapsed() * 1000000 < 1000000);
QVERIFY(t1.hasExpired(minResolution));
QVERIFY(!t1.hasExpired(8*minResolution));
QVERIFY(!t2.hasExpired(minResolution));
QVERIFY(!t1.hasExpired(-1));
QVERIFY(!t2.hasExpired(-1));
qint64 elapsed = t1.restart();
QVERIFY(elapsed > minResolution);
QVERIFY(elapsed < 3*minResolution);
qint64 diff = t2.msecsTo(t1);
QVERIFY(diff < minResolution);
auto diff = t1.msecsTo(t2);
QVERIFY2(diff > 0, QString("difference t1 and t2 is %1").arg(diff).toLatin1());
diff = t2.msecsTo(t1);
QVERIFY2(diff < 0, QString("difference t2 and t1 is %1").arg(diff).toLatin1());
}
QTEST_MAIN(tst_QElapsedTimer);