Add test for to see if the layout is stable if it has several solutions.

Currently this fails, so we have to use QEXPECT_FAIL.

1 files changed, 59 insertions, 6 deletions

diff --git a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
index 385fb3e..2c4a253 100644
--- a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
+++ b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
@@ -64,6 +64,7 @@ private slots:
     void example();
     void setSpacing();
     void hardComplexS60();
+    void stability();
     void delete_anchor();
     void conflicts();
     void sizePolicy();
@@ -986,10 +987,26 @@ void tst_QGraphicsAnchorLayout::setSpacing()
 
 }
 
-void tst_QGraphicsAnchorLayout::hardComplexS60()
+/*!
+    Taken from "hard" complex case, found at
+    https://cwiki.nokia.com/S60QTUI/AnchorLayoutComplexCases
+
+    This layout has a special property, since it has two possible solutions for its minimum size.
+
+    For instance, when it is in its minimum size - the layout have two possible solutions:
+    1. c.width == 10, e.width == 10 and g.width == 10
+       (all others have width 0)
+    2. d.width == 10 and g.width == 10
+       (all others have width 0)
+
+    It also has several solutions for preferred size.
+*/
+static QGraphicsAnchorLayout *createAmbiguousS60Layout()
 {
-    // Test for "hard" complex case, taken from wiki
-    // https://cwiki.nokia.com/S60QTUI/AnchorLayoutComplexCases
+    QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout;
+    l->setContentsMargins(0, 0, 0, 0);
+    l->setSpacing(0);
+
     QSizeF min(0, 10);
     QSizeF pref(50, 10);
     QSizeF max(100, 10);
@@ -1002,9 +1019,6 @@ void tst_QGraphicsAnchorLayout::hardComplexS60()
     QGraphicsWidget *f = createItem(min, pref, max, "f");
     QGraphicsWidget *g = createItem(min, pref, max, "g");
 
-    QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout;
-    l->setContentsMargins(0, 0, 0, 0);
-
     //<!-- Trunk -->
     setAnchor(l, l, Qt::AnchorLeft, a, Qt::AnchorLeft, 10);
     setAnchor(l, a, Qt::AnchorRight, b, Qt::AnchorLeft, 10);
@@ -1034,7 +1048,12 @@ void tst_QGraphicsAnchorLayout::hardComplexS60()
     setAnchor(l, a, Qt::AnchorBottom, d, Qt::AnchorBottom, 0);
     setAnchor(l, f, Qt::AnchorBottom, g, Qt::AnchorTop, 0);
     setAnchor(l, g, Qt::AnchorBottom, l, Qt::AnchorBottom, 0);
+    return l;
+}
 
+void tst_QGraphicsAnchorLayout::hardComplexS60()
+{
+    QGraphicsAnchorLayout *l = createAmbiguousS60Layout();
     QCOMPARE(l->count(), 7);
 
     QGraphicsWidget *p = new QGraphicsWidget(0, Qt::Window);
@@ -1050,6 +1069,40 @@ void tst_QGraphicsAnchorLayout::hardComplexS60()
 
 }
 
+void tst_QGraphicsAnchorLayout::stability()
+{
+    QVector<QRectF> geometries;
+    geometries.resize(7);
+    QGraphicsWidget *p = new QGraphicsWidget(0, Qt::Window);
+    bool sameAsPreviousArrangement = true;
+    // it usually fails after 3-4 iterations
+    for (int pass = 0; pass < 20 && sameAsPreviousArrangement; ++pass) {
+        // In case we need to "scramble" the heap allocator to provoke this bug.
+        //static const int primes[] = {2, 3, 5, 13, 89, 233, 1597, 28657, 514229}; // fibo primes
+        //const int primeCount = sizeof(primes)/sizeof(int);
+        //int alloc = primes[pass % primeCount] + pass;
+        //void *mem = qMalloc(alloc);
+        //qFree(mem);
+        QGraphicsAnchorLayout *l = createAmbiguousS60Layout();
+        p->setLayout(l);
+        QSizeF layoutMinimumSize = l->effectiveSizeHint(Qt::MinimumSize);
+        l->setGeometry(QRectF(QPointF(0,0), layoutMinimumSize));
+        QApplication::processEvents();
+        for (int i = l->count() - 1; i >=0 && sameAsPreviousArrangement; --i) {
+            QRectF geom = l->itemAt(i)->geometry();
+            if (pass != 0) {
+                sameAsPreviousArrangement = (geometries[i] == geom);
+            }
+            geometries[i] = geom;
+        }
+        p->setLayout(0);    // uninstalls and deletes the layout
+        QApplication::processEvents();
+    }
+    delete p;
+    QEXPECT_FAIL("", "The layout have several solutions, but which solution it picks is not stable", Continue);
+    QCOMPARE(sameAsPreviousArrangement, true);
+}
+
 void tst_QGraphicsAnchorLayout::delete_anchor()
 {
     QGraphicsScene scene;