find usage on Q_GLOBAL_STATIC does not work

#include "mainwindow.h"
#include "ui_mainwindow.h"

Q_GLOBAL_STATIC(QStringList, test)

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    test()->append("foo");
}

MainWindow::~MainWindow()
{
    delete ui;
    test->clear();
}