QQuickTreeView: be able to expand rows that are not yet visible in the view

If the app expands a row in TreeView, that row will for a brief moment
be expanded in the proxy model, but not in the view, until the
view is polished. For that reason, when determining if a row can be
expanded or not, we should check the state of the proxy model, and
not the view.

Note: if the application needs the state of the view to reflect the
state of the proxy model immediataly after a call to expand,
forcePolish() is always possible.

Task-number: QTBUG-91374
Change-Id: I5b85e0b5c3b32d17f93409153041df3fc2437424
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
(cherry picked from commit a43912865e294f2014f03eb7073ecd9ecf387623)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicktreeview/tst_qquicktreeview.cpp b/tests/auto/quick/qquicktreeview/tst_qquicktreeview.cpp
index c1ba0a62a5..abba5fced6 100644
--- a/tests/auto/quick/qquicktreeview/tst_qquicktreeview.cpp
+++ b/tests/auto/quick/qquicktreeview/tst_qquicktreeview.cpp
@@ -93,6 +93,7 @@ private slots:
     void expandAndCollapseRoot();
     void toggleExpanded();
     void expandAndCollapseChildren();
+    void expandChildPendingToBeVisible();
     void requiredPropertiesRoot();
     void requiredPropertiesChildren();
     void emptyModel();
@@ -359,6 +360,30 @@ void tst_qquicktreeview::insertRows()
     QCOMPARE(treeView->rows(), 9);
 }
 
+void tst_qquicktreeview::expandChildPendingToBeVisible()
+{
+    // Check that if we expand a row r1, and that row has a child r2 that can
+    // be expanded, we can continue to expand c2 immediately, even if r1 is
+    // still pending to be shown as expanded in the view.
+    LOAD_TREEVIEW("normaltreeview.qml");
+    treeView->expand(0);
+    QVERIFY(treeView->isExpanded(0));
+    // The view has not yet been updated at this point to show
+    // the newly expanded children, so it still has only one row.
+    QCOMPARE(treeView->rows(), 1);
+    // ...but we still expand row 5, which is a child that has children
+    // in the proxy model
+    treeView->expand(4);
+    QVERIFY(treeView->isExpanded(4));
+    QCOMPARE(treeView->rows(), 1);
+
+    WAIT_UNTIL_POLISHED;
+
+    // Now the view have updated to show
+    // all the rows that has been expanded.
+    QCOMPARE(treeView->rows(), 9);
+}
+
 QTEST_MAIN(tst_qquicktreeview)
 
 #include "tst_qquicktreeview.moc"