Method init

tests/test_context_menu.cpp:67–80

private slots:
    void init() {
        m_doc = new RcxDocument();
        buildTree(m_doc->tree);
        m_doc->provider = std::make_unique<BufferProvider>(makeBuffer());

        m_splitter = new QSplitter();
        m_ctrl = new RcxController(m_doc, nullptr);
        m_editor = m_ctrl->addSplitEditor(m_splitter);

        m_splitter->resize(800, 600);
        m_splitter->show();
        QVERIFY(QTest::qWaitForWindowExposed(m_splitter));
        QApplication::processEvents();
    }

    void cleanup() {
        delete m_ctrl;  m_ctrl = nullptr;