TableView: check if the model can produce items before loading

If you assign a non-empty model, the model can still return a count
of zero if something else is amiss, like the delegate being null.
So we need to do en extra check for this before we load the first
top-left item, otherwise we'll hit an assert later in the loading process.

Change-Id: I747868faf7955b8784b2957505ae03e5b1aa0b45
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 44 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp b/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
index 33437b6eac..16b3acab99 100644
--- a/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
+++ b/tests/auto/quick/qquicktableview/tst_qquicktableview.cpp
@@ -86,6 +86,7 @@ private slots:
     void emptyModel_data();
     void emptyModel();
     void checkZeroSizedDelegate();
+    void noDelegate();
     void countDelegateItems_data();
     void countDelegateItems();
     void checkLayoutOfEqualSizedDelegateItems_data();
@@ -208,6 +209,49 @@ void tst_QQuickTableView::checkZeroSizedDelegate()
     }
 }
 
+void tst_QQuickTableView::noDelegate()
+{
+    // Check that you can skip setting a delegate without
+    // it causing any problems (like crashing or asserting).
+    // And then set a delegate, and do a quick check that the
+    // view gets populated as expected.
+    LOAD_TABLEVIEW("plaintableview.qml");
+
+    const int rows = 5;
+    const int columns = 5;
+    auto model = TestModelAsVariant(columns, rows);
+    tableView->setModel(model);
+
+    // Start with no delegate, and check
+    // that we end up with no items in the table.
+    tableView->setDelegate(nullptr);
+
+    WAIT_UNTIL_POLISHED;
+
+    auto items = tableViewPrivate->loadedItems;
+    QVERIFY(items.isEmpty());
+
+    // Set a delegate, and check that we end
+    // up with the expected number of items.
+    auto delegate = view->rootObject()->property("delegate").value<QQmlComponent *>();
+    QVERIFY(delegate);
+    tableView->setDelegate(delegate);
+
+    WAIT_UNTIL_POLISHED;
+
+    items = tableViewPrivate->loadedItems;
+    QCOMPARE(items.count(), rows * columns);
+
+    // And then unset the delegate again, and check
+    // that we end up with no items.
+    tableView->setDelegate(nullptr);
+
+    WAIT_UNTIL_POLISHED;
+
+    items = tableViewPrivate->loadedItems;
+    QVERIFY(items.isEmpty());
+}
+
 void tst_QQuickTableView::countDelegateItems_data()
 {
     QTest::addColumn<QVariant>("model");