Restore Qt 4.6 behaviour: exec() always enters the event loop.

In Qt 4.6 as well as 4.7's QCoreApplication and QEventLoop, calling
exec() always enters the event loop, even if you had tried to
quit()/exit() it before entering, with one exception (noted in the
unit tests; this difference has been in Qt since at least Qt 4.2).

Add unit tests to ensure all of the three classes have the same
behaviour.

Decide if we want to match the behaviours in Qt 4.8.

Reviewed-by: Bradley T. Hughes

1 files changed, 38 insertions, 3 deletions

diff --git a/tests/auto/qeventloop/tst_qeventloop.cpp b/tests/auto/qeventloop/tst_qeventloop.cpp
index 7af722fd18..6860f194cf 100644
--- a/tests/auto/qeventloop/tst_qeventloop.cpp
+++ b/tests/auto/qeventloop/tst_qeventloop.cpp
@@ -112,6 +112,10 @@ signals:
 public:
     QMutex mutex;
     QWaitCondition cond;
+    volatile int result1;
+    volatile int result2;
+    MultipleExecThread() : result1(0xdead), result2(0xbeef) {}
+
     void run()
     {
         QMutexLocker locker(&mutex);
@@ -124,13 +128,13 @@ public:
         connect(&timer, SIGNAL(timeout()), SLOT(quit()), Qt::DirectConnection);
         timer.setInterval(1000);
         timer.start();
-        (void) exec();
+        result1 = exec();
 
         // this should return immediately, since exit() has been called
         cond.wakeOne();
         cond.wait(&mutex);
         QEventLoop eventLoop;
-        (void) eventLoop.exec();
+        result2 = eventLoop.exec();
     }
 };
 
@@ -197,7 +201,9 @@ private slots:
     void symbianNestedActiveSchedulerLoop();
     void processEvents();
     void exec();
+    void reexec();
     void exit();
+    void execAfterExit();
     void wakeUp();
     void quit();
     void processEventsExcludeSocket();
@@ -398,7 +404,9 @@ void tst_QEventLoop::exec()
     }
 
     {
-        // calling exec() after exit()/quit() should return immediately
+        // calling QEventLoop::exec() after a thread loop has exit()ed should return immediately
+        // Note: this behaviour differs from QCoreApplication and QEventLoop
+        // see tst_QCoreApplication::eventLoopExecAfterExit, tst_QEventLoop::reexec
         MultipleExecThread thread;
 
         // start thread and wait for checkpoint
@@ -411,6 +419,8 @@ void tst_QEventLoop::exec()
         thread.cond.wakeOne();
         thread.cond.wait(&thread.mutex);
         QVERIFY(spy.count() > 0);
+        int v = thread.result1;
+        QCOMPARE(v, 0);
 
         // exec should return immediately
         spy.clear();
@@ -418,6 +428,8 @@ void tst_QEventLoop::exec()
         thread.mutex.unlock();
         thread.wait();
         QCOMPARE(spy.count(), 0);
+        v = thread.result2;
+        QCOMPARE(v, -1);
     }
 
     {
@@ -462,9 +474,32 @@ void tst_QEventLoop::exec()
 #endif
 }
 
+void tst_QEventLoop::reexec()
+{
+    QEventLoop loop;
+
+    // exec once
+    QMetaObject::invokeMethod(&loop, "quit", Qt::QueuedConnection);
+    QCOMPARE(loop.exec(), 0);
+
+    // and again
+    QMetaObject::invokeMethod(&loop, "quit", Qt::QueuedConnection);
+    QCOMPARE(loop.exec(), 0);
+}
+
 void tst_QEventLoop::exit()
 { DEPENDS_ON(exec()); }
 
+void tst_QEventLoop::execAfterExit()
+{
+    QEventLoop loop;
+    EventLoopExiter obj(&loop);
+
+    QMetaObject::invokeMethod(&obj, "exit", Qt::QueuedConnection);
+    loop.exit(1);
+    QCOMPARE(loop.exec(), 0);
+}
+
 void tst_QEventLoop::wakeUp()
 {
     EventLoopThread thread;