qt5base-lts/tests/auto/testlib/selftests/float/tst_float.cpp
Jason McDonald 52744f5053 Improve float selftest
Correct a bug in the test and use unique names for data rows.  The bug
was that the test assumed that QCOMPARE for float values 100001 and
100002 would fail, but it actually succeeds.  QCOMPARE for floats uses
qFuzzyCompare(), which succeeds if the numbers differ by no more than
1/100,000th of the smaller value.  Thus QCOMPARE(100001, 100002) passes,
while QCOMPARE(99998, 99999) fails.

Change-Id: Ia35d3126c2e3ebe91d64daa309048514a365d9fb
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
2012-02-09 04:07:50 +01:00

123 lines
3.5 KiB
C++

/****************************************************************************
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#include <QtCore/QCoreApplication>
#include <QtTest/QtTest>
#include <QDebug>
class tst_float: public QObject
{
Q_OBJECT
private slots:
void floatComparisons() const;
void floatComparisons_data() const;
void compareFloatTests() const;
void compareFloatTests_data() const;
};
void tst_float::floatComparisons() const
{
QFETCH(float, operandLeft);
QFETCH(float, operandRight);
QCOMPARE(operandLeft, operandRight);
}
void tst_float::floatComparisons_data() const
{
QTest::addColumn<float>("operandLeft");
QTest::addColumn<float>("operandRight");
QTest::newRow("should SUCCEED 1")
<< float(0)
<< float(0);
QTest::newRow("should FAIL 1")
<< float(1.00000)
<< float(3.00000);
QTest::newRow("should FAIL 2")
<< float(1.00000e-7f)
<< float(3.00000e-7f);
// QCOMPARE for floats uses qFuzzyCompare(), which succeeds if the numbers
// differ by no more than 1/100,000th of the smaller value. Thus
// QCOMPARE(99998, 99999) should fail, while QCOMPARE(100001, 100002)
// should pass.
QTest::newRow("should FAIL 3")
<< float(99998)
<< float(99999);
QTest::newRow("should SUCCEED 2")
<< float(100001)
<< float(100002);
}
void tst_float::compareFloatTests() const
{
QFETCH(float, t1);
// Create two more values
// t2 differs from t1 by 1 ppm (part per million)
// t3 differs from t1 by 200%
// we should consider that t1 == t2 and t1 != t3
const float t2 = t1 + (t1 / 1e6);
const float t3 = 3 * t1;
QCOMPARE(t1, t2);
/* Should FAIL. */
QCOMPARE(t1, t3);
}
void tst_float::compareFloatTests_data() const
{
QTest::addColumn<float>("t1");
QTest::newRow("1e0") << 1e0f;
QTest::newRow("1e-7") << 1e-7f;
QTest::newRow("1e+7") << 1e+7f;
}
QTEST_MAIN(tst_float)
#include "tst_float.moc"