Flush Wayland messages in test case

A SignalSpy in QML tests frequently calls processEvents(), which
unfortunately doesn't lead to a flush of the Wayland message queue.
A workaround is implemented that forces flushing by manually emitting
the aboutToBlock signal.

Task-number: AUTOSUITE-709
Change-Id: I1480d756d9eb00d16181c9c747a3f27bce88891d
Reviewed-by: Robert Griebl <robert.griebl@qt.io>

3 files changed, 19 insertions, 5 deletions

diff --git a/src/tools/testrunner/testrunner.cpp b/src/tools/testrunner/testrunner.cpp
index 7402adad..d8837b01 100644
--- a/src/tools/testrunner/testrunner.cpp
+++ b/src/tools/testrunner/testrunner.cpp
@@ -43,6 +43,7 @@
 #include "testrunner.h"
 
 #include <QCoreApplication>
+#include <QAbstractEventDispatcher>
 #include <QEventLoop>
 #include <QQmlEngine>
 #include <QRegExp>
@@ -130,6 +131,11 @@ int AmTest::observeObjectDestroyed(QObject *obj)
     return index;
 }
 
+void AmTest::aboutToBlock()
+{
+    emit QAbstractEventDispatcher::instance()->aboutToBlock();
+}
+
 
 QTestRootObject::QTestRootObject(QObject *parent)
     : QObject(parent)
diff --git a/src/tools/testrunner/testrunner_p.h b/src/tools/testrunner/testrunner_p.h
index cf00f516..3c4cbde0 100644
--- a/src/tools/testrunner/testrunner_p.h
+++ b/src/tools/testrunner/testrunner_p.h
@@ -100,6 +100,7 @@ public:
     Q_INVOKABLE void ignoreMessage(MsgType type, const char* msg);
     Q_INVOKABLE void ignoreMessage(MsgType type, const QRegExp &expression);
     Q_INVOKABLE int observeObjectDestroyed(QObject *obj);
+    Q_INVOKABLE void aboutToBlock();
 
 Q_SIGNALS:
     void objectDestroyed(int index);
diff --git a/tests/qml/configs/tst_configs.qml b/tests/qml/configs/tst_configs.qml
index 7e92e89f..6acbb67c 100644
--- a/tests/qml/configs/tst_configs.qml
+++ b/tests/qml/configs/tst_configs.qml
@@ -42,6 +42,7 @@
 
 import QtQuick 2.4
 import QtTest 1.0
+import QtApplicationManager 2.0
 import QtApplicationManager.SystemUI 2.0
 
 
@@ -68,6 +69,13 @@ TestCase {
 
     SignalSpy {
         id: windowPropertyChangedSpy
+        // Workaround to flush Wayland messages, see https://bugreports.qt.io/browse/AUTOSUITE-709
+        // A proper solution in QtWayland is sought here: https://bugreports.qt.io/browse/QTBUG-83422
+        function aboutToBlockWait(timeout)
+        {
+            AmTest.aboutToBlock();
+            wait(timeout);
+        }
         target: WindowManager
         signalName: "windowPropertyChanged"
     }
@@ -109,13 +117,12 @@ TestCase {
         }
 
         window.setWindowProperty("trigger", "now");
-        windowPropertyChangedSpy.wait();
+        windowPropertyChangedSpy.aboutToBlockWait();
         compare(windowPropertyChangedSpy.signalArguments[0][0], window);
         compare(window.windowProperty("trigger"), "now");
 
-        // The following would only work in single-process mode (see https://bugreports.qt.io/browse/AUTOSUITE-709)
-        // windowPropertyChangedSpy.wait();
-        // compare(windowPropertyChangedSpy.signalArguments[1][0], window);
-        // compare(window.windowProperty("ack"), "done");
+        windowPropertyChangedSpy.wait();
+        compare(windowPropertyChangedSpy.signalArguments[1][0], window);
+        compare(window.windowProperty("ack"), "done");
     }
 }