Maintain at least 500ms timestamp distance between each test function

If we had one test function that just did

tst_Mouse::f1()
{
    QTest::mouseMove(w, QPoint(0,0));
}

and another test function that did

tst_Mouse::f2()
{
    QTest::mouseMove(w, QPoint(500,500));
}

their corresponding event timestamps were only 1 apart from each other.
This meant that any code that tried to estimate the velocity of a mouse
cursor would get a really high velocity estimate inside f2(). This would
come as a surprise to most people. So to avoid this, we add a 500 ms
timestamp delay between each test function call.

In theory this could also prevent generating a mouseDoubleClickEvent
when a pair of test functions containing a press-release sequence was
run, but there is a separate pre-existing mechanism to handle that case.

Change-Id: Icd4fc35853c09f080466d22411208c7b5c4174b5
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

src/testlib/qtestcase.cpp

@@ -296,6 +296,8 @@ namespace QTestPrivate
 
 namespace QTest
 {
+extern Q_TESTLIB_EXPORT int lastMouseTimestamp;
+
 class WatchDog;
 
 static QObject *currentTestObject = nullptr;
@@ -1173,6 +1175,7 @@ bool TestMethods::invokeTest(int index, const char *data, WatchDog *watchDog) co
                 QTestPrivate::qtestMouseButtons = Qt::NoButton;
                 if (watchDog)
                     watchDog->beginTest();
+                QTest::lastMouseTimestamp += 500;   // Maintain at least 500ms mouse event timestamps between each test function call
                 invokeTestOnData(index);
                 if (watchDog)
                     watchDog->testFinished();

tests/auto/testlib/selftests/mouse/tst_mouse.cpp

@@ -42,6 +42,8 @@ class tst_Mouse : public QObject
     Q_OBJECT
 
 private slots:
+    void timestampBetweenTestFunction_data();
+    void timestampBetweenTestFunction();
     void stateHandlingPart1_data();
     void stateHandlingPart1();
     void stateHandlingPart2();
@@ -55,20 +57,83 @@ public:
     Qt::MouseButtons stateInMouseMove = Qt::NoButton;
     int moveCount = 0;
     int pressCount = 0;
+    int doubleClickCount = 0;
+    ulong lastTimeStamp = 0;
 
 protected:
-    void mousePressEvent(QMouseEvent *)
+    void mousePressEvent(QMouseEvent *e)
     {
         pressCount++;
+        processEvent(e);
     }
 
     void mouseMoveEvent(QMouseEvent *e)
     {
         moveCount++;
         stateInMouseMove = e->buttons();
+        processEvent(e);
     }
+
+    void mouseReleaseEvent(QMouseEvent *e)
+    {
+        processEvent(e);
+    }
+
+    void mouseDoubleClickEvent(QMouseEvent *e)
+    {
+        doubleClickCount++;
+        processEvent(e);
+    }
+
+    void processEvent(QMouseEvent *e)
+    {
+        lastTimeStamp = e->timestamp();
+    }
+
 };
 
+static ulong lastTimeStampInPreviousTestFunction = 0;
+
+void tst_Mouse::timestampBetweenTestFunction_data()
+{
+    QTest::addColumn<bool>("hoverLast");
+    QTest::addColumn<bool>("pressAndRelease");
+    QTest::newRow("press, release") << true << false;
+    QTest::newRow("press, release, hover") << true << true;
+    QTest::newRow("hover") << false << true;
+    QTest::newRow("hover #2") << false << true;
+    QTest::newRow("press, release #2") << true << false;
+    QTest::newRow("press, release, hover #2") << true << true;
+}
+
+void tst_Mouse::timestampBetweenTestFunction()
+{
+    QFETCH(bool, hoverLast);
+    QFETCH(bool, pressAndRelease);
+
+    MouseWindow w;
+    w.show();
+    w.setGeometry(100, 100, 200, 200);
+    QVERIFY(QTest::qWaitForWindowActive(&w));
+
+    QPoint point(10, 10);
+    QCOMPARE(w.pressCount, 0);
+    if (pressAndRelease) {
+        QTest::mousePress(&w, Qt::LeftButton, { }, point);
+        QVERIFY(w.lastTimeStamp - lastTimeStampInPreviousTestFunction > 500);   // Should be at least 500 ms timestamp between each test case
+        QCOMPARE(w.pressCount, 1);
+        QTest::mouseRelease(&w, Qt::LeftButton, { }, point);
+    }
+    QCOMPARE(w.doubleClickCount, 0);
+    if (hoverLast) {
+        static int xMove = 0;
+        xMove += 5;     // Just make sure we generate different hover coordinates
+        point.rx() += xMove;
+        QTest::mouseMove(&w, point);     // a hover move. This doesn't generate a timestamp delay of 500 ms
+    }
+    lastTimeStampInPreviousTestFunction = w.lastTimeStamp;
+}
+
 void tst_Mouse::stateHandlingPart1_data()
 {
     QTest::addColumn<bool>("dummy");