QTest: add qWait(chrono::milliseconds) overload

The code bailed out of the while loop when "remainingTime <= 0",
for a QDeadlineTimer::isForever() timer remainingTime() returns -1,
whereas remainingTimeAsDuration() returns nanoseconds::max().

I.e. the original code stopped the while loop when the timer isForever()
or "expired" (i.e. remaining time is 0). I am not sure the isForever()
part was intended that way or not, but it makes sense, if
QCoreApplication::processEvents() has already run "forever", there is no
point looping again.

[ChangeLog][QtCore][QTest] Added qWait(chrono::milliseconds) overload.

Change-Id: I871c28b053c6ba4f81a7e2d434aa4fbe03c8c5e7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/kernel/qtestsupport_core.cpp

@@ -68,10 +68,23 @@ void QTest::qSleep(std::chrono::milliseconds msecs)
     \since 5.10
 */
 
+/*!
+    \overload
 
-/*! \fn void QTest::qWait(int ms)
+    Waits for \a msecs. Equivalent to calling:
+    \code
+    QTest::qWait(std::chrono::milliseconds{msecs});
+    \endcode
+*/
+Q_CORE_EXPORT void QTest::qWait(int msecs)
+{
+    qWait(std::chrono::milliseconds{msecs});
+}
 
-    Waits for \a ms milliseconds. While waiting, events will be processed and
+/*!
+    \since 6.7
+
+    Waits for \a msecs. While waiting, events will be processed and
     your test will stay responsive to user interface events or network communication.
 
     Example:
@@ -83,7 +96,7 @@ void QTest::qSleep(std::chrono::milliseconds msecs)
 
     \sa QTest::qSleep(), QSignalSpy::wait()
 */
-Q_CORE_EXPORT void QTest::qWait(int ms)
+Q_CORE_EXPORT void QTest::qWait(std::chrono::milliseconds msecs)
 {
     // Ideally this method would be implemented in terms of qWaitFor(), with a
     // predicate that always returns false, but qWaitFor() uses the 1-arg overload
@@ -93,17 +106,24 @@ Q_CORE_EXPORT void QTest::qWait(int ms)
 
     Q_ASSERT(QCoreApplication::instance());
 
-    QDeadlineTimer timer(ms, Qt::PreciseTimer);
-    int remaining = ms;
+    using namespace std::chrono;
+
+    QDeadlineTimer deadline(msecs, Qt::PreciseTimer);
+
     do {
-        QCoreApplication::processEvents(QEventLoop::AllEvents, remaining);
+        QCoreApplication::processEvents(QEventLoop::AllEvents, deadline);
         QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete);
-        remaining = timer.remainingTime();
-        if (remaining <= 0)
+
+        // If dealine is Forever, processEvents() has already looped forever
+        if (deadline.isForever())
             break;
-        QTest::qSleep(qMin(10, remaining));
-        remaining = timer.remainingTime();
-    } while (remaining > 0);
+
+        msecs = ceil<milliseconds>(deadline.remainingTimeAsDuration());
+        if (msecs == 0ms)
+            break;
+
+        QTest::qSleep(std::min(10ms, msecs));
+    } while (!deadline.hasExpired());
 }
 
 QT_END_NAMESPACE

src/corelib/kernel/qtestsupport_core.h

@@ -54,6 +54,8 @@ template <typename Functor>
 
 Q_CORE_EXPORT void qWait(int ms);
 
+Q_CORE_EXPORT void qWait(std::chrono::milliseconds msecs);
+
 } // namespace QTest
 
 QT_END_NAMESPACE

src/testlib/doc/snippets/code/src_corelib_kernel_qtestsupport_core.cpp

@@ -18,9 +18,10 @@ int myNetworkServerNotResponding()
 int MyObject::isReady()
 {
 //! [1]
+    using namespace std::chrono_literals;
     int i = 0;
     while (myNetworkServerNotResponding() && i++ < 50)
-        QTest::qWait(250);
+        QTest::qWait(250ms);
 //! [1]
 return 1;
 }