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, 222 insertions, 0 deletions

diff --git a/tests/auto/testlib/selftests/mouse/mouse.pro b/tests/auto/testlib/selftests/mouse/mouse.pro
new file mode 100644
index 0000000000..7c06b8aa64
--- /dev/null
+++ b/tests/auto/testlib/selftests/mouse/mouse.pro
@@ -0,0 +1,7 @@
+SOURCES += tst_mouse.cpp
+QT += testlib testlib-private gui gui-private
+
+mac:CONFIG -= app_bundle
+CONFIG -= debug_and_release_target
+
+TARGET = mouse
diff --git a/tests/auto/testlib/selftests/mouse/tst_mouse.cpp b/tests/auto/testlib/selftests/mouse/tst_mouse.cpp
new file mode 100644
index 0000000000..3c731cde69
--- /dev/null
+++ b/tests/auto/testlib/selftests/mouse/tst_mouse.cpp
@@ -0,0 +1,215 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest>
+#include <QtGui/QWindow>
+#include <QtGui/QCursor>
+#include <QtGui/private/qguiapplication_p.h>
+
+QT_BEGIN_NAMESPACE
+namespace QTestPrivate {
+extern Q_TESTLIB_EXPORT Qt::MouseButtons qtestMouseButtons; // from qtestcase.cpp
+}
+QT_END_NAMESPACE
+
+class tst_Mouse : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void stateHandlingPart1_data();
+    void stateHandlingPart1();
+    void stateHandlingPart2();
+    void deterministicEvents_data();
+    void deterministicEvents();
+};
+
+class MouseWindow : public QWindow
+{
+public:
+    Qt::MouseButtons stateInMouseMove = Qt::NoButton;
+    int moveCount = 0;
+    int pressCount = 0;
+
+protected:
+    void mousePressEvent(QMouseEvent *)
+    {
+        pressCount++;
+    }
+
+    void mouseMoveEvent(QMouseEvent *e)
+    {
+        moveCount++;
+        stateInMouseMove = e->buttons();
+    }
+};
+
+void tst_Mouse::stateHandlingPart1_data()
+{
+    QTest::addColumn<bool>("dummy");
+    QTest::newRow("dummy-1") << true;
+    QTest::newRow("dummy-2") << true;
+}
+
+void tst_Mouse::stateHandlingPart1()
+{
+    QFETCH(bool, dummy);
+    Q_UNUSED(dummy);
+
+    QWindow w;
+    w.setFlags(w.flags() | Qt::FramelessWindowHint); // ### FIXME: QTBUG-63542
+    w.show();
+    w.setGeometry(100, 100, 200, 200);
+    QVERIFY(QTest::qWaitForWindowActive(&w));
+
+    QPoint point(10, 10);
+    QPoint step(1, 1);
+
+    // verify that we have a clean state after the previous data set
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::NoButton);
+
+    QTest::mousePress(&w, Qt::LeftButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::LeftButton);
+    QTest::mousePress(&w, Qt::RightButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::LeftButton | Qt::RightButton);
+    QTest::mouseMove(&w, point += step);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::LeftButton | Qt::RightButton);
+    QTest::mouseRelease(&w, Qt::LeftButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::RightButton);
+    QTest::mouseMove(&w, point += step);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::RightButton);
+    // test invalid input - left button was already released
+    QTest::mouseRelease(&w, Qt::LeftButton, 0, point += point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::RightButton);
+    // test invalid input - right button is already pressed
+    QTest::mousePress(&w, Qt::RightButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::RightButton);
+    // now continue with valid input
+    QTest::mouseRelease(&w, Qt::RightButton, 0, point += point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::NoButton);
+    QTest::mouseMove(&w, point += step);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::NoButton);
+
+    // exit this test function with some button in a pressed state
+    QTest::mousePress(&w, Qt::LeftButton, 0, point);
+    QTest::mousePress(&w, Qt::RightButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::LeftButton | Qt::RightButton);
+}
+
+void tst_Mouse::stateHandlingPart2()
+{
+    MouseWindow w;
+    w.setFlags(w.flags() | Qt::FramelessWindowHint); // ### FIXME: QTBUG-63542
+    w.show();
+    w.setGeometry(100, 100, 200, 200);
+    QVERIFY(QTest::qWaitForWindowActive(&w));
+
+    // verify that we have a clean state after stateHandlingPart1()
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::NoButton);
+
+#if !QT_CONFIG(cursor)
+    QSKIP("This part of the test requires the QCursor API");
+#else
+    // The windowing system's view on a current button state might be different
+    // from the qtestlib's mouse button state. This test verifies that the mouse
+    // events generated by the system are adjusted to reflect qtestlib's view
+    // on the current button state.
+    // SKIP: not convinced yet that there is a valid use case for this.
+
+    QSKIP("Not implemented beyond this point!");
+
+    QPoint point(40, 40);
+    QTest::mousePress(&w, Qt::LeftButton, 0, point);
+    QTest::mousePress(&w, Qt::RightButton, 0, point);
+    QCOMPARE(QTestPrivate::qtestMouseButtons, Qt::LeftButton | Qt::RightButton);
+    w.moveCount = 0;
+    // The windowing system will send mouse events with no buttons set
+    QPoint moveToPoint = w.mapToGlobal(point + QPoint(1, 1));
+    if (QCursor::pos() == moveToPoint)
+        moveToPoint += QPoint(1, 1);
+    QCursor::setPos(moveToPoint);
+    QTRY_COMPARE(w.moveCount, 1);
+    // Verify that qtestlib adjusted the button state
+    QCOMPARE(w.stateInMouseMove, Qt::LeftButton | Qt::RightButton);
+#endif
+}
+
+void tst_Mouse::deterministicEvents_data()
+{
+    QTest::addColumn<bool>("firstRun");
+    QTest::newRow("first-run-true") << true;
+    QTest::newRow("first-run-false") << false;
+}
+
+void tst_Mouse::deterministicEvents()
+{
+    /* QGuiApplication uses QGuiApplicationPrivate::lastCursorPosition to
+    determine if it needs to generate an additional mouse move event for
+    mouse press/release. Verify that this property is reset to it's default
+    value, ensuring deterministic event generation behavior. Not resetting
+    this value might affect event generation for subsequent tests runs (in
+    unlikely case where a subsquent test does a mouse press in a pos that is
+    equal to QGuiApplicationPrivate::lastCursorPosition, not causing mouse
+    move to be generated.
+    NOTE: running this test alone as in "./mouse deterministicEvents:first-run-false"
+    won't test what this test is designed to test. */
+
+    QSKIP("Not implemented!");
+
+    /* It is undecided how and at what scope we want to handle reseting
+    lastCursorPosition, or perhaps Qt should not be generating mouse move
+    events as documented in QGuiApplicationPrivate::processMouseEvent(),
+    then the problem would go away - ### Qt6 ? */
+
+    QVERIFY(qIsInf(QGuiApplicationPrivate::lastCursorPosition.x()));
+    QVERIFY(qIsInf(QGuiApplicationPrivate::lastCursorPosition.y()));
+
+    QFETCH(bool, firstRun);
+
+    MouseWindow w;
+    w.setFlags(w.flags() | Qt::FramelessWindowHint); // ### FIXME: QTBUG-63542
+    w.show();
+    w.setGeometry(100, 100, 200, 200);
+    QVERIFY(QTest::qWaitForWindowActive(&w));
+
+    QCOMPARE(w.pressCount, 0);
+    QCOMPARE(w.moveCount, 0);
+    static QPoint m_cachedLastCursorPosition;
+    if (firstRun) {
+        QTest::mousePress(&w, Qt::LeftButton, 0, QPoint(40, 40));
+        m_cachedLastCursorPosition = QGuiApplicationPrivate::lastCursorPosition.toPoint();
+    } else {
+        QPoint point = w.mapFromGlobal(m_cachedLastCursorPosition);
+        QTest::mousePress(&w, Qt::LeftButton, 0, point);
+    }
+    QCOMPARE(w.pressCount, 1);
+    QCOMPARE(w.moveCount, 1);
+}
+
+QTEST_MAIN(tst_Mouse)
+#include "tst_mouse.moc"