Fix restoring expanded URLs

When navigating back or forward in history, DolphinView tells the
KFileItemModel about the expanded URLs which should be restored before
the folder is entered. In this case, the algorithm in the new function
KFileItemModel::setExpanded(const QSet<KUrl>&) does not work. To fix
this, the old function
KFileItemModel::restoreExpandedUrls(const QSet<KUrl>&) is restored.

Unit test included.

4 files changed, 25 insertions, 2 deletions

diff --git a/src/kitemviews/kfileitemmodel.cpp b/src/kitemviews/kfileitemmodel.cpp
index 363503b02..040309dc3 100644
--- a/src/kitemviews/kfileitemmodel.cpp
+++ b/src/kitemviews/kfileitemmodel.cpp
@@ -431,6 +431,11 @@ QSet<KUrl> KFileItemModel::expandedUrls() const
     return m_expandedUrls;
 }
 
+void KFileItemModel::restoreExpandedUrls(const QSet<KUrl>& urls)
+{
+    m_urlsToExpand = urls;
+}
+
 void KFileItemModel::setExpanded(const QSet<KUrl>& urls)
 {
 
diff --git a/src/kitemviews/kfileitemmodel.h b/src/kitemviews/kfileitemmodel.h
index a049f6766..17524b82a 100644
--- a/src/kitemviews/kfileitemmodel.h
+++ b/src/kitemviews/kfileitemmodel.h
@@ -122,6 +122,13 @@ public:
     QSet<KUrl> expandedUrls() const;
 
     /**
+     * Marks the URLs in \a urls as subfolders which were expanded previously.
+     * They are re-expanded one by one each time the KDirLister's completed() signal is received.
+     * Note that a manual triggering of the KDirLister is required.
+     */
+    void restoreExpandedUrls(const QSet<KUrl>& urls);
+
+    /**
      * Expands all parent-items of each URL given by \a urls.
      */
     void setExpanded(const QSet<KUrl>& urls);
diff --git a/src/tests/kfileitemmodeltest.cpp b/src/tests/kfileitemmodeltest.cpp
index f2d62fbad..59e817fff 100644
--- a/src/tests/kfileitemmodeltest.cpp
+++ b/src/tests/kfileitemmodeltest.cpp
@@ -451,7 +451,7 @@ void KFileItemModelTest::testExpandItems()
     QVERIFY(m_model->expandedUrls().empty());
 
     m_dirLister->openUrl(m_testDir->url());
-    m_model->setExpanded(allFolders);
+    m_model->restoreExpandedUrls(allFolders);
     QVERIFY(QTest::kWaitForSignal(m_model, SIGNAL(loadingCompleted()), DefaultTimeout));
     QCOMPARE(m_model->count(), 5);  // 5 items: "a/", "a/a/", "a/a/1", "a/a-1/", "a/a-1/1"
     QVERIFY(m_model->isExpanded(0));
@@ -460,6 +460,17 @@ void KFileItemModelTest::testExpandItems()
     QVERIFY(m_model->isExpanded(3));
     QVERIFY(!m_model->isExpanded(4));
     QCOMPARE(m_model->expandedUrls(), allFolders);
+
+    // Move to a sub folder, then call restoreExpandedFolders() *before* going back.
+    // This is how DolphinView restores the expanded folders when navigating in history.
+    m_dirLister->openUrl(KUrl(m_testDir->name() + "a/a/"));
+    QVERIFY(QTest::kWaitForSignal(m_model, SIGNAL(loadingCompleted()), DefaultTimeout));
+    QCOMPARE(m_model->count(), 1);  // 1 item: "1"
+    m_model->restoreExpandedUrls(allFolders);
+    m_dirLister->openUrl(m_testDir->url());
+    QVERIFY(QTest::kWaitForSignal(m_model, SIGNAL(loadingCompleted()), DefaultTimeout));
+    QCOMPARE(m_model->count(), 5);  // 5 items: "a/", "a/a/", "a/a/1", "a/a-1/", "a/a-1/1"
+    QCOMPARE(m_model->expandedUrls(), allFolders);
 }
 
 void KFileItemModelTest::testSorting()
diff --git a/src/views/dolphinview.cpp b/src/views/dolphinview.cpp
index 578b93a2b..91d668e9d 100644
--- a/src/views/dolphinview.cpp
+++ b/src/views/dolphinview.cpp
@@ -943,7 +943,7 @@ void DolphinView::restoreState(QDataStream& stream)
     // Restore expanded folders (only relevant for the details view - will be ignored by the view in other view modes)
     QSet<KUrl> urls;
     stream >> urls;
-    fileItemModel()->setExpanded(urls);
+    fileItemModel()->restoreExpandedUrls(urls);
 }
 
 void DolphinView::saveState(QDataStream& stream)