Move the formatting of <chrono> durations to QDebug & QtTest

[ChangeLog][QtCore][QDebug] Added pretty formatting of C++ <chrono>
durations.

[ChangeLog][QtTest] Added pretty formatting of C++ <chrono> durations
for QCOMPARE expressions.

Change-Id: I3b169860d8bd41e9be6bfffd1757cc087ba957fa
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

9 files changed, 388 insertions, 46 deletions

diff --git a/src/corelib/io/qdebug.cpp b/src/corelib/io/qdebug.cpp
index 0a72696a37..56deeb7cf7 100644
--- a/src/corelib/io/qdebug.cpp
+++ b/src/corelib/io/qdebug.cpp
@@ -15,6 +15,8 @@
 #include <private/qtextstream_p.h>
 #include <private/qtools_p.h>
 
+#include <q20chrono.h>
+
 QT_BEGIN_NAMESPACE
 
 using namespace QtMiscUtils;
@@ -346,6 +348,90 @@ void QDebug::putByteArray(const char *begin, size_t length, Latin1Content conten
 }
 
 /*!
+    \since 6.6
+    \internal
+    Helper to the std::chrono::duration debug streaming output.
+ */
+QByteArray QDebug::timeUnit(qint64 num, qint64 den)
+{
+    using namespace std::chrono;
+    using namespace q20::chrono;
+
+    if (num == 1 && den > 1) {
+        // sub-multiple of seconds
+        char prefix = '\0';
+        auto tryprefix = [&](auto d, char c) {
+            static_assert(decltype(d)::num == 1, "not an SI prefix");
+            if (den == decltype(d)::den)
+                prefix = c;
+        };
+
+        // "u" should be "µ", but debugging output is not always UTF-8-safe
+        tryprefix(std::milli{}, 'm');
+        tryprefix(std::micro{}, 'u');
+        tryprefix(std::nano{}, 'n');
+        tryprefix(std::pico{}, 'p');
+        tryprefix(std::femto{}, 'f');
+        tryprefix(std::atto{}, 'a');
+        // uncommon ones later
+        tryprefix(std::centi{}, 'c');
+        tryprefix(std::deci{}, 'd');
+        if (prefix) {
+            char unit[3] = { prefix, 's' };
+            return QByteArray(unit, sizeof(unit) - 1);
+        }
+    }
+
+    const char *unit = nullptr;
+    if (num > 1 && den == 1) {
+        // multiple of seconds - but we don't use SI prefixes
+        auto tryunit = [&](auto d, const char *name) {
+            static_assert(decltype(d)::period::den == 1, "not a multiple of a second");
+            if (unit || num % decltype(d)::period::num)
+                return;
+            unit = name;
+            num /= decltype(d)::period::num;
+        };
+        tryunit(years{}, "yr");
+        tryunit(weeks{}, "wk");
+        tryunit(days{}, "d");
+        tryunit(hours{}, "h");
+        tryunit(minutes{}, "min");
+    }
+    if (!unit)
+        unit = "s";
+
+    if (num == 1 && den == 1)
+        return unit;
+    if (Q_UNLIKELY(num < 1 || den < 1))
+        return QString::asprintf("<invalid time unit %lld/%lld>", num, den).toLatin1();
+
+    // uncommon units: will return something like "[2/3]s"
+    //  strlen("[/]min") = 6
+    char buf[2 * (std::numeric_limits<qint64>::digits10 + 2) + 10];
+    size_t len = 0;
+    auto appendChar = [&](char c) {
+        Q_ASSERT(len < sizeof(buf));
+        buf[len++] = c;
+    };
+    auto appendNumber = [&](qint64 value) {
+        if (value >= 10'000 && (value % 1000) == 0)
+            len += qsnprintf(buf + len, sizeof(buf) - len, "%.6g", double(value));  // "1e+06"
+        else
+            len += qsnprintf(buf + len, sizeof(buf) - len, "%lld", value);
+    };
+    appendChar('[');
+    appendNumber(num);
+    if (den != 1) {
+        appendChar('/');
+        appendNumber(den);
+    }
+    appendChar(']');
+    memcpy(buf + len, unit, strlen(unit));
+    return QByteArray(buf, len + strlen(unit));
+}
+
+/*!
     \fn QDebug::swap(QDebug &other)
     \since 5.0
 
@@ -777,6 +863,18 @@ QDebug &QDebug::resetFormat()
 */
 
 /*!
+    \since 6.6
+    \fn template <typename Rep, typename Period> QDebug &QDebug::operator<<(std::chrono::duration<Rep, Period> duration)
+
+    Prints the time duration \a duration to the stream and returns a reference
+    to the stream. The printed string is the numeric representation of the
+    period followed by the time unit, similar to what the C++ Standard Library
+    would produce with \c{std::ostream}.
+
+    The unit is not localized.
+*/
+
+/*!
     \fn template <class T> QString QDebug::toString(T &&object)
     \since 6.0
 
diff --git a/src/corelib/io/qdebug.h b/src/corelib/io/qdebug.h
index e39f9afd31..3fa9c42052 100644
--- a/src/corelib/io/qdebug.h
+++ b/src/corelib/io/qdebug.h
@@ -16,6 +16,7 @@
 #include <QtCore/qsharedpointer.h>
 
 // all these have already been included by various headers above, but don't rely on indirect includes:
+#include <chrono>
 #include <list>
 #include <map>
 #include <string>
@@ -67,6 +68,7 @@ class QT6_ONLY(Q_CORE_EXPORT) QDebug : public QIODeviceBase
     QT7_ONLY(Q_CORE_EXPORT) void putUcs4(uint ucs4);
     QT7_ONLY(Q_CORE_EXPORT) void putString(const QChar *begin, size_t length);
     QT7_ONLY(Q_CORE_EXPORT) void putByteArray(const char *begin, size_t length, Latin1Content content);
+    QT7_ONLY(Q_CORE_EXPORT) static QByteArray timeUnit(qint64 num, qint64 den);
 public:
     explicit QDebug(QIODevice *device) : stream(new Stream(device)) {}
     explicit QDebug(QString *string) : stream(new Stream(string)) {}
@@ -189,6 +191,13 @@ public:
     { return *this << QString::fromUcs4(s.data(), s.size()); }
 #endif // !Q_QDOC
 
+    template <typename Rep, typename Period>
+    QDebug &operator<<(std::chrono::duration<Rep, Period> duration)
+    {
+        stream->ts << duration.count() << timeUnit(Period::num, Period::den);
+        return maybeSpace();
+    }
+
     template <typename T>
     static QString toString(T &&object)
     {
diff --git a/src/testlib/qtest.h b/src/testlib/qtest.h
index 175affebcf..73278791ca 100644
--- a/src/testlib/qtest.h
+++ b/src/testlib/qtest.h
@@ -356,6 +356,19 @@ template<> inline char *toString(const QCborMap &m)
     return Internal::QCborValueFormatter::format(m);
 }
 
+template <typename Rep, typename Period> char *toString(std::chrono::duration<Rep, Period> dur)
+{
+    QString r;
+    QDebug d(&r);
+    d.nospace() << qSetRealNumberPrecision(9) << dur;
+    if constexpr (Period::num != 1 || Period::den != 1) {
+        // include the equivalent value in seconds, in parentheses
+        using namespace std::chrono;
+        d << " (" << duration_cast<duration<qreal>>(dur).count() << "s)";
+    }
+    return qstrdup(std::move(r).toUtf8().constData());
+}
+
 template <typename T1, typename T2>
 inline char *toString(const std::pair<T1, T2> &pair)
 {
diff --git a/src/testlib/qtestcase.h b/src/testlib/qtestcase.h
index 3e0b2b3fb3..bd65c0ecab 100644
--- a/src/testlib/qtestcase.h
+++ b/src/testlib/qtestcase.h
@@ -360,6 +360,9 @@ namespace QTest
     template <class... Types>
     inline char *toString(const std::tuple<Types...> &tuple);
 
+    template <typename Rep, typename Period>
+    inline char *toString(std::chrono::duration<Rep, Period> duration);
+
     Q_TESTLIB_EXPORT char *toHexRepresentation(const char *ba, qsizetype length);
     Q_TESTLIB_EXPORT char *toPrettyCString(const char *unicode, qsizetype length);
     Q_TESTLIB_EXPORT char *toPrettyUnicode(QStringView string);
diff --git a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
index a54018c3fa..37bb6aa65a 100644
--- a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
+++ b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
@@ -16,6 +16,8 @@
 #include <QMimeDatabase>
 #include <QMetaType>
 
+#include <q20chrono.h>
+
 #ifdef __cpp_lib_memory_resource
 # include <memory_resource>
 namespace pmr = std::pmr;
@@ -23,6 +25,8 @@ namespace pmr = std::pmr;
 namespace pmr = std;
 #endif
 
+using namespace std::chrono;
+using namespace q20::chrono;
 using namespace Qt::StringLiterals;
 
 static_assert(QTypeTraits::has_ostream_operator_v<QDebug, int>);
@@ -83,6 +87,8 @@ private slots:
     void qDebugQByteArray() const;
     void qDebugQByteArrayView() const;
     void qDebugQFlags() const;
+    void qDebugStdChrono_data() const;
+    void qDebugStdChrono() const;
     void textStreamModifiers() const;
     void resetFormat() const;
     void defaultMessagehandler() const;
@@ -1102,6 +1108,107 @@ void tst_QDebug::qDebugQFlags() const
     QCOMPARE(s_msg, QString::fromLatin1("QFlags<tst_QDebug::FlagType>(EnumFlag1)"));
 }
 
+using ToStringFunction = std::function<QString()>;
+void tst_QDebug::qDebugStdChrono_data() const
+{
+    using attoseconds = duration<int64_t, std::atto>;
+    using femtoseconds = duration<int64_t, std::femto>;
+    using picoseconds = duration<int64_t, std::pico>;
+    using centiseconds = duration<int64_t, std::centi>;
+    using deciseconds = duration<int64_t, std::deci>;
+
+    using quadriennia = duration<int, std::ratio_multiply<std::ratio<4>, years::period>>;
+    using decades = duration<int, std::ratio_multiply<years::period, std::deca>>; // decayears
+    using centuries = duration<int16_t, std::ratio_multiply<years::period, std::hecto>>; // hectoyears
+    using millennia = duration<int16_t, std::ratio_multiply<years::period, std::kilo>>; // kiloyears
+    using gigayears = duration<int8_t, std::ratio_multiply<years::period, std::giga>>;
+    using fortnights = duration<int, std::ratio_multiply<days::period, std::ratio<14>>>;
+    using microfortnights = duration<int64_t, std::ratio_multiply<fortnights::period, std::micro>>;
+    using telecom = duration<int64_t, std::ratio<1, 8000>>; // 8 kHz
+
+    using kiloseconds = duration<int64_t, std::kilo>;
+    using exaseconds = duration<int8_t, std::exa>;
+    using meter_per_light = duration<int64_t, std::ratio<1, 299'792'458>>;
+    using kilometer_per_light = duration<int64_t, std::ratio<1000, 299'792'458>>;
+
+    QTest::addColumn<ToStringFunction>("fn");
+    QTest::addColumn<QString>("expected");
+
+    auto addRow = [](const char *name, auto duration, const char *expected) {
+        auto toString = [duration]() { return QDebug::toString(duration); };
+        QTest::newRow(name) << ToStringFunction(toString) << expected;
+    };
+
+    addRow("1as", attoseconds{1}, "1as");
+    addRow("1fs", femtoseconds{1}, "1fs");
+    addRow("1ps", picoseconds{1}, "1ps");
+    addRow("0ns", 0ns, "0ns");
+    addRow("1000ns", 1000ns, "1000ns");
+    addRow("0us", 0us, "0us");
+    addRow("0ms", 0ms, "0ms");
+    addRow("1cs", centiseconds{1}, "1cs");
+    addRow("2ds", deciseconds{2}, "2ds");
+    addRow("-1s", -1s, "-1s");
+    addRow("0s", 0s, "0s");
+    addRow("1s", 1s, "1s");
+    addRow("60s", 60s, "60s");
+    addRow("1min", 1min, "1min");
+    addRow("1h", 1h, "1h");
+    addRow("1days", days{1}, "1d");
+    addRow("365days", days{365}, "365d");
+    addRow("1weeks", weeks{1}, "1wk");
+    addRow("1years", years{1}, "1yr"); // 365.2425 days
+    addRow("42years", years{42}, "42yr");
+
+    addRow("1ks", kiloseconds{1}, "1[1000]s");
+    addRow("2fortnights", fortnights{2}, "2[2]wk");
+    addRow("1quadriennia", quadriennia{1}, "1[4]yr");
+    addRow("1decades", decades{1}, "1[10]yr");
+    addRow("1centuries", centuries{1}, "1[100]yr");
+    addRow("1millennia", millennia{1}, "1[1000]yr");
+#if defined(Q_OS_LINUX) || defined(Q_OS_DARWIN)
+    // some OSes print the exponent differently
+    addRow("1Es", exaseconds{1}, "1[1e+18]s");
+    addRow("13gigayears", gigayears{13}, "13[1e+09]yr");
+#endif
+
+    // months are one twelfth of a Gregorian year, not 30 days
+    addRow("1months", months{1}, "1[2629746]s");
+
+    // weird units
+    addRow("2microfortnights", microfortnights{2}, "2[756/625]s");
+    addRow("1telecom", telecom{1}, "1[1/8000]s");
+    addRow("10m/c", meter_per_light{10}, "10[1/299792458]s");
+    addRow("10km/c", kilometer_per_light{10}, "10[500/149896229]s");
+
+    // real floting point
+    using fpsec = duration<double>;
+    using fpmsec = duration<double, std::milli>;
+    using fpnsec = duration<double, std::nano>;
+    addRow("1.0s", fpsec{1}, "1s");
+    addRow("1.5s", fpsec{1.5}, "1.5s");
+    addRow("1.0ms", fpmsec{1}, "1ms");
+    addRow("1.5ms", fpmsec{1.5}, "1.5ms");
+    addRow("1.0ns", fpnsec{1}, "1ns");
+    addRow("1.5ns", fpnsec{1.5}, "1.5ns");
+
+    // and some precision setting too
+    QTest::newRow("1.00000ns")
+            << ToStringFunction([]() {
+        QString buffer;
+        QDebug d(&buffer);
+        d.nospace() << qSetRealNumberPrecision(5) << Qt::fixed << fpnsec{1};
+        return buffer;
+    }) << "1.00000ns";
+}
+
+void tst_QDebug::qDebugStdChrono() const
+{
+    QFETCH(ToStringFunction, fn);
+    QFETCH(QString, expected);
+    QCOMPARE(fn(), expected);
+}
+
 void tst_QDebug::textStreamModifiers() const
 {
     QString file, function;
diff --git a/tests/auto/corelib/kernel/qdeadlinetimer/tst_qdeadlinetimer.cpp b/tests/auto/corelib/kernel/qdeadlinetimer/tst_qdeadlinetimer.cpp
index bdf2e7a573..a584cda9fc 100644
--- a/tests/auto/corelib/kernel/qdeadlinetimer/tst_qdeadlinetimer.cpp
+++ b/tests/auto/corelib/kernel/qdeadlinetimer/tst_qdeadlinetimer.cpp
@@ -27,52 +27,6 @@ template<> char *toString(const QDeadlineTimer &dt)
               dt.hasExpired() ? " (expired)" : "");
     return buf;
 }
-
-template <typename Rep, typename Period> char *toString(std::chrono::duration<Rep, Period> dur)
-{
-    using namespace std::chrono;
-    static_assert(sizeof(double) == sizeof(qlonglong));
-
-    if constexpr (Period::num == 1 && sizeof(Rep) <= sizeof(qlonglong)) {
-        // typical case: second or sub-multiple of second, in a representation
-        // we can directly use
-        char *buf = new char[128];
-        if constexpr (std::is_integral_v<Rep>) {
-            char unit[] = "ss";
-            if constexpr (std::is_same_v<Period, std::atto>) {  // from Norwegian "atten", 18
-                unit[0] = 'a';
-            } else if constexpr (std::is_same_v<Period, std::femto>) {  // Norwegian "femten", 15
-                unit[0] = 'f';
-            } else if constexpr (std::is_same_v<Period, std::pico>) {
-                unit[0] = 'p';
-            } else if constexpr (std::is_same_v<Period, std::nano>) {
-                unit[0] = 'n';
-            } else if constexpr (std::is_same_v<Period, std::micro>) {
-                unit[0] = 'u';      // µ, really, but the output may not be UTF-8-safe
-            } else if constexpr (std::is_same_v<Period, std::milli>) {
-                unit[0] = 'm';
-            } else {
-                // deci, centi, cycles of something (60 Hz, 8000 Hz, etc.)
-                static_assert(Period::den == 1,
-                        "Unsupported std::chrono::duration of a sub-multiple of second");
-                unit[1] = '\0';
-            }
-
-            // cast to qlonglong in case Rep is not int64_t
-            qsnprintf(buf, 128, "%lld %s", qlonglong(dur.count()), unit);
-        } else {
-            auto secs = duration_cast<duration<double>>(dur);
-            qsnprintf(buf, 128, "%g s", secs.count());
-        }
-        return buf;
-    } else if constexpr (std::is_integral_v<Rep> && Period::den == 1) {
-        // multiple of second, so just print it in seconds
-        return toString(std::chrono::seconds(dur));
-    } else {
-        // something else, use floating-point seconds
-        return toString(std::chrono::duration_cast<double>(dur));
-    }
-}
 }
 QT_END_NAMESPACE
 
diff --git a/tests/auto/testlib/CMakeLists.txt b/tests/auto/testlib/CMakeLists.txt
index 1f8438fa64..35a26a8e34 100644
--- a/tests/auto/testlib/CMakeLists.txt
+++ b/tests/auto/testlib/CMakeLists.txt
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 add_subdirectory(qsignalspy)
+add_subdirectory(tostring)
 
 # QTBUG-88507
 if(QT_FEATURE_process AND NOT ANDROID)
diff --git a/tests/auto/testlib/tostring/CMakeLists.txt b/tests/auto/testlib/tostring/CMakeLists.txt
new file mode 100644
index 0000000000..57fc65d352
--- /dev/null
+++ b/tests/auto/testlib/tostring/CMakeLists.txt
@@ -0,0 +1,7 @@
+# Copyright (C) 2023 Intel Corporation.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_internal_add_test(tst_tostring
+    SOURCES
+        tst_tostring.cpp
+)
diff --git a/tests/auto/testlib/tostring/tst_tostring.cpp b/tests/auto/testlib/tostring/tst_tostring.cpp
new file mode 100644
index 0000000000..3f12e0c798
--- /dev/null
+++ b/tests/auto/testlib/tostring/tst_tostring.cpp
@@ -0,0 +1,150 @@
+// Copyright (C) 2023 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QTest>
+#include <memory>
+
+#include <q20chrono.h>
+
+using ToStringFunction = std::function<char *()>;
+class tst_toString : public QObject
+{
+    Q_OBJECT
+private:
+    void addColumns();
+    void testRows();
+private slots:
+    void chrono_duration_data();
+    void chrono_duration() { testRows(); }
+};
+
+void tst_toString::addColumns()
+{
+    QTest::addColumn<ToStringFunction>("fn");
+    QTest::addColumn<QByteArrayView>("expected");
+    QTest::addColumn<QByteArrayView>("expr");
+    QTest::addColumn<QByteArrayView>("file");
+    QTest::addColumn<int>("line");
+}
+void tst_toString::testRows()
+{
+    QFETCH(ToStringFunction, fn);
+    QFETCH(QByteArrayView, expected);
+    QFETCH(QByteArrayView, expr);
+    QFETCH(QByteArrayView, file);
+    QFETCH(int, line);
+
+    std::unique_ptr<char []> ptr{fn()};
+    QTest::qCompare(ptr.get(), expected, expr.data(), expected.data(), file.data(), line);
+}
+
+template <typename T> void addRow(QByteArrayView name, T &&value, QByteArrayView expression,
+                                  QByteArrayView expected, QByteArrayView file, int line)
+{
+    ToStringFunction fn = [v = std::move(value)]() { return QTest::toString(v); };
+    QTest::newRow(name.data()) << fn << expected << expression << file << line;
+}
+
+#define ADD_ROW(name, expr, expected)         \
+    ::addRow(name, expr, #expr, expected, __FILE__, __LINE__)
+
+void tst_toString::chrono_duration_data()
+{
+    addColumns();
+
+    using namespace std::chrono;
+    using namespace q20::chrono;
+
+    using attoseconds = duration<int64_t, std::atto>;
+    using femtoseconds = duration<int64_t, std::femto>;
+    using picoseconds = duration<int64_t, std::pico>;
+    using centiseconds = duration<int64_t, std::centi>;
+    using deciseconds = duration<int64_t, std::deci>;
+    using kiloseconds = duration<int64_t, std::kilo>;
+    using decades = duration<int, std::ratio_multiply<years::period, std::deca>>; // decayears
+    using centuries = duration<int16_t, std::ratio_multiply<years::period, std::hecto>>; // hectoyears
+    using millennia = duration<int16_t, std::ratio_multiply<years::period, std::kilo>>; // kiloyears
+    using gigayears = duration<int8_t, std::ratio_multiply<years::period, std::giga>>;
+    using fortnights = duration<int, std::ratio_multiply<days::period, std::ratio<14>>>;
+    using microfortnights = duration<int64_t, std::ratio_multiply<fortnights::period, std::micro>>;
+    using meter_per_light = duration<int64_t, std::ratio<1, 299'792'458>>;
+    using kilometer_per_light = duration<int64_t, std::ratio<1000, 299'792'458>>;
+    using AU_per_light = duration<int64_t, std::ratio<149'597'871'800, 299'792'458>>;
+    using pstn_rate = duration<int64_t, std::ratio<1, 8000>>; // PSTN sampling rate (8 kHz)
+    using hyperfine = duration<int64_t, std::ratio<1, 9'192'631'770>>;  // definition of second
+
+    ADD_ROW("1as", attoseconds{1}, "1as (1e-18s)");   // from Norwegian "atten" (18)
+    ADD_ROW("1fs", femtoseconds{1}, "1fs (1e-15s)");  // from Norwegian "femten" (15)
+    ADD_ROW("1ps", picoseconds{1}, "1ps (1e-12s)");   // from Italian piccolo?
+    ADD_ROW("0ns", 0ns, "0ns (0s)");
+    ADD_ROW("1000ns", 1000ns, "1000ns (1e-06s)");
+    ADD_ROW("1us", 1us, "1us (1e-06s)");
+    ADD_ROW("125us", 125us, "125us (0.000125s)");
+    ADD_ROW("0ms", 0ms, "0ms (0s)");
+    ADD_ROW("-1s", -1s, "-1s");
+    ADD_ROW("0s", 0s, "0s");
+    ADD_ROW("1cs", centiseconds{1}, "1cs (0.01s)");
+    ADD_ROW("2ds", deciseconds{2}, "2ds (0.2s)");
+    ADD_ROW("1s", 1s, "1s");
+    ADD_ROW("60s", 60s, "60s");
+    ADD_ROW("1min", 1min, "1min (60s)");
+    ADD_ROW("1h", 1h, "1h (3600s)");
+    ADD_ROW("1days", days{1}, "1d (86400s)");
+    ADD_ROW("7days", days{7}, "7d (604800s)");
+    ADD_ROW("1weeks", weeks{1}, "1wk (604800s)");
+    ADD_ROW("365days", days{365}, "365d (31536000s)");
+    ADD_ROW("1years", years{1}, "1yr (31556952s)"); // 365.2425 days
+
+    ADD_ROW("2ks", kiloseconds{2}, "2[1000]s (2000s)");
+    ADD_ROW("1fortnights", fortnights{1}, "1[2]wk (1209600s)");
+    ADD_ROW("1decades", decades{1}, "1[10]yr (315569520s)");
+    ADD_ROW("1centuries", centuries{1}, "1[100]yr (3.1556952e+09s)");
+    ADD_ROW("1millennia", millennia{1}, "1[1000]yr (3.1556952e+10s)");
+#if defined(Q_OS_LINUX) || defined(Q_OS_DARWIN)
+    // some OSes print the exponent differently
+    ADD_ROW("13gigayears", gigayears{13}, "13[1e+09]yr (4.10240376e+17s)");
+#endif
+
+    // months are one twelfth of a Gregorian year, not 30 days
+    ADD_ROW("1months", months{1}, "1[2629746]s (2629746s)");
+    ADD_ROW("12months", months{12}, "12[2629746]s (31556952s)");
+
+    // weird units
+    ADD_ROW("2microfortnights", microfortnights{2}, "2[756/625]s (2.4192s)");
+    ADD_ROW("1pstn_rate", pstn_rate{1}, "1[1/8000]s (0.000125s)");   // 125µs
+    ADD_ROW("10m/c", meter_per_light{10}, "10[1/299792458]s (3.33564095e-08s)");
+    ADD_ROW("10km/c", kilometer_per_light{10}, "10[500/149896229]s (3.33564095e-05s)");
+    ADD_ROW("1AU/c", AU_per_light{1}, "1[74798935900/149896229]s (499.004788s)");
+    ADD_ROW("Cs133-hyperfine", hyperfine{1}, "1[1/9192631770]s (1.08782776e-10s)");
+    ADD_ROW("1sec-definition", hyperfine{9'192'631'770}, "9192631770[1/9192631770]s (1s)");
+    ADD_ROW("8000pstn_rate", pstn_rate{8000}, "8000[1/8000]s (1s)");
+
+    // real floting point
+    // current (2023) best estimate is 13.813 ± 0.038 billion years (Plank Collaboration)
+    using universe = duration<double, std::ratio_multiply<std::ratio<13'813'000'000>, years::period>>;
+    using fpksec = duration<double, std::kilo>;
+    using fpsec = duration<double>;
+    using fpmsec = duration<double, std::milli>;
+    using fpnsec = duration<double, std::nano>;
+    using fpGyr = duration<double, std::ratio_multiply<years::period, std::giga>>;
+
+    ADD_ROW("1.0s", fpsec{1}, "1s");
+    ADD_ROW("1.5s", fpsec{1.5}, "1.5s");
+    ADD_ROW("-1.0ms", fpmsec{-1}, "-1ms (-0.001s)");
+    ADD_ROW("1.5ms", fpmsec{1.5}, "1.5ms (0.0015s)");
+    ADD_ROW("1.0ns", fpnsec{1}, "1ns (1e-09s)");
+    ADD_ROW("-1.5ns", fpnsec{-1.5}, "-1.5ns (-1.5e-09s)");
+    ADD_ROW("1.0ks", fpksec{1}, "1[1000]s (1000s)");
+    ADD_ROW("-1.5ks", fpksec{-1.5}, "-1.5[1000]s (-1500s)");
+    ADD_ROW("1.0zs", fpsec{1e-21}, "1e-21s");  // zeptosecond
+    ADD_ROW("1.0ys", fpsec{1e-24}, "1e-24s");  // yoctosecond
+    ADD_ROW("planck-time", fpsec(5.39124760e-44), "5.3912476e-44s");
+#if defined(Q_OS_LINUX) || defined(Q_OS_DARWIN)
+    // some OSes print the exponent differently
+    ADD_ROW("13.813Gyr", fpGyr(13.813), "13.813[1e+09]yr (4.35896178e+17s)");
+    ADD_ROW("1universe", universe{1}, "1[1.3813e+10]yr (4.35896178e+17s)");
+#endif
+}
+
+QTEST_APPLESS_MAIN(tst_toString)
+#include "tst_tostring.moc"