QTest::mouseClick does not trigger context menu

#include <QString>
#include <QTest>
#include <QCoreApplication>
#include <QMainWindow>
#include <QStandardItemModel>
#include <QTreeView>
#include <QSignalSpy>

class Test : public QObject
{
    Q_OBJECT

private Q_SLOTS:
    void testMouseClickContextMenu();
};

void Test::testMouseClickContextMenu()
{
    QMainWindow w;
    QStandardItemModel *model = new QStandardItemModel();
    QStandardItem *item = new QStandardItem("Test");
    model->appendRow({item});
    QTreeView *tree = new QTreeView();
    tree->setModel(model);
    w.setCentralWidget(tree);

    tree->setContextMenuPolicy(Qt::CustomContextMenu);

    QSignalSpy spy(tree, SIGNAL(customContextMenuRequested(QPoint)));
    QTest::mouseClick(tree, Qt::RightButton, 0,
                      tree->visualRect(item->index()).center());
    QCOMPARE(spy.size(), 1); //Actual is 0
}

QTEST_MAIN(Test)

#include "tst_test.moc"

Config: Using QtTest library 5.5.1, Qt 5.5.1 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 4.9.1 20140922 (Red Hat 4.9.1-10))
PASS   : Test::initTestCase()
FAIL!  : Test::testMouseClickContextMenu() Compared values are not the same
   Actual   (spy.size()): 0
   Expected (1)         : 1
   Loc: [../qt-sandbox/tst_test.cpp(32)]
PASS   : Test::cleanupTestCase()
Totals: 2 passed, 1 failed, 0 skipped, 0 blacklisted