Add a helper class for waiting for model changes in tests

The tests are using complicated logic when waiting for model changes.
This patch introduces a new WaitHelper class, which uses a QPromise to
indicate the start and finish of a task, and QFutureWatcher to wait for
the associated future to finish. This class will be reused in other
parts of code, where waiting is required.

Task-number: QTBUG-90688
Pick-to: 5.15
Change-Id: I4a412fa555be342c168e526601f8fc56d5091872
Reviewed-by: Brett Stottlemyer <bstottle@ford.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/tests/auto/shared/model_utilities.h b/tests/auto/shared/model_utilities.h
index 7e30382..b1044a5 100644
--- a/tests/auto/shared/model_utilities.h
+++ b/tests/auto/shared/model_utilities.h
@@ -29,6 +29,48 @@
 #include <QtTest/QtTest>
 #include <QModelIndex>
 
+// Helper class which can be used by tests for starting a task and
+// waiting for its completion. It takes care of running an event
+// loop while waiting, until finished() method is called (or the
+// timeout is reached).
+class WaitHelper : public QObject
+{
+    Q_OBJECT
+
+public:
+    WaitHelper() { m_promise.reportStarted(); }
+
+    ~WaitHelper()
+    {
+        if (m_promise.future().isRunning())
+            m_promise.reportFinished();
+    }
+
+    /*
+        Starts an event loop and waits until finish() method is called
+        or the timeout is reached.
+    */
+    bool wait(int timeout = 30000)
+    {
+        if (m_promise.future().isFinished())
+            return true;
+
+        QFutureWatcher<void> watcher;
+        QSignalSpy watcherSpy(&watcher, &QFutureWatcher<void>::finished);
+        watcher.setFuture(m_promise.future());
+        return watcherSpy.wait(timeout);
+    }
+
+protected:
+    /*
+        The derived classes need to call this method to stop waiting.
+    */
+    void finish() { m_promise.reportFinished(); }
+
+private:
+    QFutureInterface<void> m_promise;
+};
+
 namespace {
 
 inline bool compareIndices(const QModelIndex &lhs, const QModelIndex &rhs)