Add testlib selftests for double and for non-finite float and double

Tidied up the existing float tests in the process.
(In particular, s/SUCCESS/PASS/ since that matches real test output.)
These verify that QCOMPARE() handles floats and doubles as intended.
Extended the existing qFuzzyCompare tests to probe the boundaries of
the ranges of values of both types, in the process.

Revised the toString<double> that qCompare() uses to give enough
precision to actually show some of the differences being tested there
(12 digits, to match what qFuzzyCompare tests, so as to show different
values rather than, e.g. 1e12 for both expected and actual) and to
give consistent results for infinities and NaN (MinGW had eccentric
versions for these, leading to different output from tests, which thus
failed); did the latter also for toString<float> and fixed stray zeros
in MinGW's exponents (which made a kludge in tst_selftest.cpp
redundant, so I removed that, too).

That's further complicated handling of floating-point types, so let's
just keep an eye on how expensive that's getting by adding a benchmark
test for QTest::toString().  Unfortunately, default settings only get
runs that take modest numbers of milliseconds (some as low as 40)
while increasing this with -minumumvalue 100 or more gets the process
killed - and I'm unable to find out who's doing the killing (it's not
QProcess::kill, ::kill or the QtTest WatchDog, as far as I can tell).
So results are rather noisy; the integral tests exhibit speed-ups by
factors up to 5, and slow-downs by factors up to 100, between runs
with and without this change, which does not affec the integral tests.
The relatively modest slow-downs and speed-ups in the floating point
tests thus seem likely to be happenstance rather than signal.

Change-Id: I4a6bbbab6a43bf14a4089e96238a7c8da2c3127e
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 130 insertions, 20 deletions

diff --git a/tests/auto/testlib/selftests/float/tst_float.cpp b/tests/auto/testlib/selftests/float/tst_float.cpp
index 2fffcc7803..babb588f4b 100644
--- a/tests/auto/testlib/selftests/float/tst_float.cpp
+++ b/tests/auto/testlib/selftests/float/tst_float.cpp
@@ -30,16 +30,92 @@
 #include <QtTest/QtTest>
 #include <QDebug>
 
+// Test proper handling of floating-point types
 class tst_float: public QObject
 {
     Q_OBJECT
 private slots:
+    void doubleComparisons() const;
+    void doubleComparisons_data() const;
     void floatComparisons() const;
     void floatComparisons_data() const;
     void compareFloatTests() const;
     void compareFloatTests_data() const;
 };
 
+void tst_float::doubleComparisons() const
+{
+    QFETCH(double, operandLeft);
+    QFETCH(double, operandRight);
+
+    QCOMPARE(operandLeft, operandRight);
+}
+
+void tst_float::doubleComparisons_data() const
+{
+    QTest::addColumn<double>("operandLeft");
+    QTest::addColumn<double>("operandRight");
+
+    QTest::newRow("should PASS 1") << 0. << 0.;
+    QTest::newRow("should FAIL 1") << 1.00000 << 3.00000;
+    QTest::newRow("should FAIL 2") << 1.00000e-7 << 3.00000e-7;
+
+    // QCOMPARE for doubles uses qFuzzyCompare(), which succeeds if the numbers
+    // differ by no more than 1e-12 times the smaller value.  Thus
+    // QCOMPARE(1e12-2, 1e12-1) should fail, while QCOMPARE(1e12+1, 1e12+2)
+    // should pass.
+
+    QTest::newRow("should PASS 2") << 1e12 + 1. << 1e12 + 2.;
+    QTest::newRow("should FAIL 3") << 1e12 - 1. << 1e12 - 2.;
+    // ... but rounding makes that a bit unrelaible when scaled close to the bounds.
+    QTest::newRow("should PASS 3") << 1e-310 + 1e-322 << 1e-310 + 2e-322;
+    QTest::newRow("should FAIL 4") << 1e-310 - 1e-322 << 1e-310 - 3e-322;
+    QTest::newRow("should PASS 4") << 1e307 + 1e295 << 1e307 + 2e295;
+    QTest::newRow("should FAIL 5") << 1e307 - 1e295 << 1e307 - 3e295;
+
+    // QCOMPARE special-cases non-finite values
+    if (std::numeric_limits<double>::has_quiet_NaN) {
+        const double nan = std::numeric_limits<double>::quiet_NaN();
+        QTest::newRow("should PASS: NaN == NaN") << nan << nan;
+        QTest::newRow("should FAIL: NaN != 0") << nan << 0.;
+        QTest::newRow("should FAIL: 0 != NaN") << 0. << nan;
+        QTest::newRow("should FAIL: NaN != 1") << nan << 1.;
+        QTest::newRow("should FAIL: 1 != NaN") << 1. << nan;
+    }
+    if (std::numeric_limits<double>::has_infinity) {
+        const double uge = std::numeric_limits<double>::infinity();
+        QTest::newRow("should PASS: inf == inf") << uge << uge;
+        QTest::newRow("should PASS: -inf == -inf") << -uge << -uge;
+        QTest::newRow("should FAIL: inf != -inf") << uge << -uge;
+        QTest::newRow("should FAIL: -inf != inf") << -uge << uge;
+        if (std::numeric_limits<double>::has_quiet_NaN) {
+            const double nan = std::numeric_limits<double>::quiet_NaN();
+            QTest::newRow("should FAIL: inf != nan") << uge << nan;
+            QTest::newRow("should FAIL: nan != inf") << nan << uge;
+            QTest::newRow("should FAIL: -inf != nan") << -uge << nan;
+            QTest::newRow("should FAIL: nan != -inf") << nan << -uge;
+        }
+        QTest::newRow("should FAIL: inf != 0") << uge << 0.;
+        QTest::newRow("should FAIL: 0 != inf") << 0. << uge;
+        QTest::newRow("should FAIL: -inf != 0") << -uge << 0.;
+        QTest::newRow("should FAIL: 0 != -inf") << 0. << -uge;
+        QTest::newRow("should FAIL: inf != 1") << uge << 1.;
+        QTest::newRow("should FAIL: 1 != inf") << 1. << uge;
+        QTest::newRow("should FAIL: -inf != 1") << -uge << 1.;
+        QTest::newRow("should FAIL: 1 != -inf") << 1. << -uge;
+
+        const double big = std::numeric_limits<double>::max();
+        QTest::newRow("should FAIL: inf != max") << uge << big;
+        QTest::newRow("should FAIL: inf != -max") << uge << -big;
+        QTest::newRow("should FAIL: max != inf") << big << uge;
+        QTest::newRow("should FAIL: -max != inf") << -big << uge;
+        QTest::newRow("should FAIL: -inf != max") << -uge << big;
+        QTest::newRow("should FAIL: -inf != -max") << -uge << -big;
+        QTest::newRow("should FAIL: max != -inf") << big << -uge;
+        QTest::newRow("should FAIL: -max != -inf") << -big << -uge;
+    }
+}
+
 void tst_float::floatComparisons() const
 {
     QFETCH(float, operandLeft);
@@ -53,30 +129,64 @@ 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);
+    QTest::newRow("should FAIL 1") << 1.00000f << 3.00000f;
+    QTest::newRow("should PASS 1") << 0.f << 0.f;
+    QTest::newRow("should FAIL 2") << 1.00000e-7f << 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)
+    // differ by no more than 1e-5 times the smaller value.  Thus
+    // QCOMPARE(1e5-2, 1e5-1) should fail, while QCOMPARE(1e5+1, 1e5+2)
     // should pass.
 
-    QTest::newRow("should FAIL 3")
-        << float(99998)
-        << float(99999);
-
-    QTest::newRow("should SUCCEED 2")
-        << float(100001)
-        << float(100002);
+    QTest::newRow("should PASS 2") << 1e5f + 1.f << 1e5f + 2.f;
+    QTest::newRow("should FAIL 3") << 1e5f - 1.f << 1e5f - 2.f;
+    // ... but rounding makes that a bit unrelaible when scaled close to the bounds.
+    QTest::newRow("should PASS 3") << 1e-39f + 1e-44f << 1e-39f + 2e-44f;
+    QTest::newRow("should FAIL 4") << 1e-39f - 1e-44f << 1e-39f - 3e-44f;
+    QTest::newRow("should PASS 4") << 1e38f + 1e33f << 1e38f + 2e33f;
+    QTest::newRow("should FAIL 5") << 1e38f - 1e33f << 1e38f - 3e33f;
+
+    // QCOMPARE special-cases non-finite values
+    if (std::numeric_limits<float>::has_quiet_NaN) {
+        const float nan = std::numeric_limits<float>::quiet_NaN();
+        QTest::newRow("should PASS: NaN == NaN") << nan << nan;
+        QTest::newRow("should FAIL: NaN != 0") << nan << 0.f;
+        QTest::newRow("should FAIL: 0 != NaN") << 0.f << nan;
+        QTest::newRow("should FAIL: NaN != 1") << nan << 1.f;
+        QTest::newRow("should FAIL: 1 != NaN") << 1.f << nan;
+    }
+    if (std::numeric_limits<float>::has_infinity) {
+        const float uge = std::numeric_limits<float>::infinity();
+        QTest::newRow("should PASS: inf == inf") << uge << uge;
+        QTest::newRow("should PASS: -inf == -inf") << -uge << -uge;
+        QTest::newRow("should FAIL: inf != -inf") << uge << -uge;
+        QTest::newRow("should FAIL: -inf != inf") << -uge << uge;
+        if (std::numeric_limits<float>::has_quiet_NaN) {
+            const float nan = std::numeric_limits<float>::quiet_NaN();
+            QTest::newRow("should FAIL: inf != nan") << uge << nan;
+            QTest::newRow("should FAIL: nan != inf") << nan << uge;
+            QTest::newRow("should FAIL: -inf != nan") << -uge << nan;
+            QTest::newRow("should FAIL: nan != -inf") << nan << -uge;
+        }
+        QTest::newRow("should FAIL: inf != 0") << uge << 0.f;
+        QTest::newRow("should FAIL: 0 != inf") << 0.f << uge;
+        QTest::newRow("should FAIL: -inf != 0") << -uge << 0.f;
+        QTest::newRow("should FAIL: 0 != -inf") << 0.f << -uge;
+        QTest::newRow("should FAIL: inf != 1") << uge << 1.f;
+        QTest::newRow("should FAIL: 1 != inf") << 1.f << uge;
+        QTest::newRow("should FAIL: -inf != 1") << -uge << 1.f;
+        QTest::newRow("should FAIL: 1 != -inf") << 1.f << -uge;
+
+        const float big = std::numeric_limits<float>::max();
+        QTest::newRow("should FAIL: inf != max") << uge << big;
+        QTest::newRow("should FAIL: inf != -max") << uge << -big;
+        QTest::newRow("should FAIL: max != inf") << big << uge;
+        QTest::newRow("should FAIL: -max != inf") << -big << uge;
+        QTest::newRow("should FAIL: -inf != max") << -uge << big;
+        QTest::newRow("should FAIL: -inf != -max") << -uge << -big;
+        QTest::newRow("should FAIL: max != -inf") << big << -uge;
+        QTest::newRow("should FAIL: -max != -inf") << -big << -uge;
+    }
 }
 
 void tst_float::compareFloatTests() const