qtestlib: fix support for pressing multiple mouse buttons

After a37785ec7638e7485112b87dd7e767881fecc114 went in, it become
apparent that multi mouse button state handling in qtestlib is
non-existent, for details see QTBUG-64030 and QTBUG-63786. What
happened behind the scenes often was not what one would expect based
on the provided QTest::mouse* input sequence - events went missing,
incorrect events were generated, each subsequent test function
started with a state set from the function that run earlier. It is
easy to see how a minor change in one test could easily affect outcome
of other tests.

With a37785ec7638e7485112b87dd7e767881fecc114, Qt platform plugins
are now responsible for sending explicit mouse button type and state
information; qtestlib should take full responsibility now as well.
But using the new API from a37785ec7 alone in qtestlib is not sufficient.
We need to reset mouse state between each new test function run (we do
this at function scope as that fits with the current qtestlib API user
expectations). This patch implements the necessary reseting logic.

Updated tst_qwindow.cpp::generatedMouseMove() to use QTest::mouse* APIs.
That test requires pressing multiple buttons, it was not possible with
QTest::mouse* APIs before this patch.

Added an auto test for multiple mouse button pressing/release in
tests/auto/testlib/selftests/mouse/. And few other tests which are
currently QSKIP-ed, but should be considered when re-designing qtestlib
APIs.

Task-number: QTBUG-64030
Change-Id: I39fdcbc73a467a7463ce2aed622bf22484095635
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 24 insertions, 8 deletions

diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index 497470464f..7e9c03dbd4 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -268,6 +268,11 @@ static bool isValidSlot(const QMetaMethod &sl)
         || name == "init" || name == "cleanup");
 }
 
+namespace QTestPrivate
+{
+    Q_TESTLIB_EXPORT Qt::MouseButtons qtestMouseButtons = Qt::NoButton;
+}
+
 namespace QTest
 {
     class WatchDog;
@@ -1074,6 +1079,7 @@ bool TestMethods::invokeTest(int index, const char *data, WatchDog *watchDog) co
                     QTestDataSetter s(curDataIndex >= dataCount ? static_cast<QTestData *>(0)
                                                       : table.testData(curDataIndex));
 
+                    QTestPrivate::qtestMouseButtons = Qt::NoButton;
                     if (watchDog)
                         watchDog->beginTest();
                     invokeTestOnData(index);
diff --git a/src/testlib/qtestmouse.h b/src/testlib/qtestmouse.h
index fa524fd8ca..e2835828a1 100644
--- a/src/testlib/qtestmouse.h
+++ b/src/testlib/qtestmouse.h
@@ -68,11 +68,16 @@ Q_GUI_EXPORT void qt_handleMouseEvent(QWindow *window, const QPointF &local, con
                                       Qt::MouseButtons state, Qt::MouseButton button,
                                       QEvent::Type type, Qt::KeyboardModifiers mods, int timestamp);
 
+namespace QTestPrivate
+{
+    extern Q_TESTLIB_EXPORT Qt::MouseButtons qtestMouseButtons;
+}
+
 namespace QTest
 {
     enum MouseAction { MousePress, MouseRelease, MouseClick, MouseDClick, MouseMove };
 
-    extern Q_TESTLIB_EXPORT Qt::MouseButton lastMouseButton;
+    extern Q_TESTLIB_EXPORT Qt::MouseButton lastMouseButton; // ### unsued
     extern Q_TESTLIB_EXPORT int lastMouseTimestamp;
 
     // This value is used to emulate timestamps to avoid creating double clicks by mistake.
@@ -117,30 +122,35 @@ namespace QTest
         QPointF global = window->mapToGlobal(pos);
         QPointer<QWindow> w(window);
 
+        using namespace QTestPrivate;
         switch (action)
         {
         case MouseDClick:
-            qt_handleMouseEvent(w, pos, global, button, button, QEvent::MouseButtonPress,
+            qtestMouseButtons.setFlag(button, true);
+            qt_handleMouseEvent(w, pos, global, qtestMouseButtons, button, QEvent::MouseButtonPress,
                                 stateKey, ++lastMouseTimestamp);
-            qt_handleMouseEvent(w, pos, global, Qt::NoButton, button, QEvent::MouseButtonRelease,
+            qtestMouseButtons.setFlag(button, false);
+            qt_handleMouseEvent(w, pos, global, qtestMouseButtons, button, QEvent::MouseButtonRelease,
                                 stateKey, ++lastMouseTimestamp);
             Q_FALLTHROUGH();
         case MousePress:
         case MouseClick:
-            qt_handleMouseEvent(w, pos, global, button, button, QEvent::MouseButtonPress,
+            qtestMouseButtons.setFlag(button, true);
+            qt_handleMouseEvent(w, pos, global, qtestMouseButtons, button, QEvent::MouseButtonPress,
                                 stateKey, ++lastMouseTimestamp);
-            lastMouseButton = button;
+            lastMouseButton = button; // ### unsued
             if (action == MousePress)
                 break;
             Q_FALLTHROUGH();
         case MouseRelease:
-            qt_handleMouseEvent(w, pos, global, Qt::NoButton, button, QEvent::MouseButtonRelease,
+            qtestMouseButtons.setFlag(button, false);
+            qt_handleMouseEvent(w, pos, global, qtestMouseButtons, button, QEvent::MouseButtonRelease,
                                 stateKey, ++lastMouseTimestamp);
             lastMouseTimestamp += mouseDoubleClickInterval; // avoid double clicks being generated
-            lastMouseButton = Qt::NoButton;
+            lastMouseButton = Qt::NoButton; // ### unsued
             break;
         case MouseMove:
-            qt_handleMouseEvent(w, pos, global, lastMouseButton, Qt::NoButton, QEvent::MouseMove,
+            qt_handleMouseEvent(w, pos, global, qtestMouseButtons, Qt::NoButton, QEvent::MouseMove,
                                 stateKey, ++lastMouseTimestamp);
             break;
         default: