I'm trying to test QTableView with custom model and several delegates (combobox and spinbox).

Init test case

void TestGuiDelegateWithTableView::initTestCase()
{
    user_data_t d{{"foo", 2}, {"bar", 4}, {"baz", 6}};
    table = new QTableView;
    table->setModel(new Model);
    table->setItemDelegateForColumn(0, new DelegateCombobox(std::move(d)));
    table->setItemDelegateForColumn(1, new DelegateSpinbox({-10., 10.}));
}

Combobox with userdata

Combobox delegate has a constructor which takes std::vector<std::pair<QString, int>> the collection of display and user role values.

    QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const override
    {
        auto* box{new QComboBox(parent)};
        for (const auto& [text, user] : _data) {
            box->addItem(text, user);
        }
        return box;
    }

The test _data method works perfectly (or it is simple coincidence):

    QTest::addColumn<QTestEventList>("events");
    QTest::addColumn<QString>("display");
    QTest::addColumn<int>("user");

    const auto cell = table->model()->index(0, 0);
    const auto center = table->visualRect(cell).center();

    {
        QTestEventList events;
        events.addMouseClick(Qt::LeftButton, Qt::NoModifier, center, 50);
        events.addMouseDClick(Qt::LeftButton, Qt::NoModifier, center, 100);
        events.addKeyPress(Qt::Key_Down);
        events.addKeyPress(Qt::Key_Enter);
        QTest::newRow("e1") << events << "foo" << 2;
    }

But when I try to achieve the second or the third combobox element as below:

    {
        QTestEventList events;
        events.addMouseClick(Qt::LeftButton, Qt::NoModifier, center, 50);
        events.addMouseDClick(Qt::LeftButton, Qt::NoModifier, center, 100);
        events.addKeyPress(Qt::Key_Down, Qt::NoModifier, 10);
        events.addKeyPress(Qt::Key_Down, Qt::NoModifier, 10);
        events.addKeyPress(Qt::Key_Enter);
        QTest::newRow("e2") << events << "bar" << 4;
    }

    {
        QTestEventList events;
        events.addMouseClick(Qt::LeftButton, Qt::NoModifier, center, 50);
        events.addMouseDClick(Qt::LeftButton, Qt::NoModifier, center, 100);
        events.addKeyPress(Qt::Key_Down);
        events.addKeyPress(Qt::Key_Down);
        events.addKeyPress(Qt::Key_Down);
        events.addKeyPress(Qt::Key_Enter);
        QTest::newRow("e3") << events << "baz" << 6;
    }

its do not work.

Calling code:

{
    QFETCH(QTestEventList, events);
    QFETCH(QString, display);
    QFETCH(int, user);

    QVERIFY2(table->viewport(), "Should be not empty");
    events.simulate(table->viewport());
    QCOMPARE(table->model()->index(0, 0).data(Qt::DisplayRole).toString(), display);
    QCOMPARE(table->model()->index(0, 0).data(Qt::UserRole).toInt(), user);
}

Spinbox with range

Also I'm trying to test spinbox:

    QVERIFY2(table, "Should be not empty");
    QVERIFY2(table->model(), "Should be not empty");

    const auto cell = table->model()->index(0, 1);
    const auto center = table->visualRect(cell).center();
    QTest::mouseClick(table->viewport(), Qt::LeftButton, Qt::NoModifier, center);
    QTest::mouseDClick(table->viewport(), Qt::LeftButton, Qt::NoModifier, center);
    QTest::keyClicks(table->viewport()->focusWidget(),"-9.54");
    QTest::keyPress(table->viewport()->focusWidget(), Qt::Key_Enter);

    const auto actual = table->model()->index(0, 1).data(Qt::DisplayRole).toString();
    QCOMPARE(actual, "-9.54");

Model

Set data

    bool setData(const QModelIndex& index, const QVariant& value, int role) override
    {
        if (const auto col = index.column(); col == 0) {
            if (const auto row = index.row(); role == Qt::DisplayRole) {
                _display[row] = value.toString();
                return true;
            }
            else if (role == Qt::UserRole) {
                _user[row] = value.toInt();
                return true;
            }
        } else if (col == 1) {
            if (role == Qt::DisplayRole) {
                _spin[index.row()] = value.toDouble();
                return true;
            }
        }
    return false;
    }

data()

    [[nodiscard]] QVariant data(const QModelIndex& index, int role) const override
    {
        if (const auto col = index.column(); col == 0) {
            if (const auto row = index.row(); role == Qt::DisplayRole) {
                return _display[row];
            }
            else if (role == Qt::UserRole) {
                return _user[row];
            }
        } else if (col == 1 && role == Qt::DisplayRole) {
            return _spin[index.row()];
        }

        return {};
    }

private storage fields:

  private:
    std::array<QString, 3> _display{};
    std::array<int, 3> _user{};
    std::array<double, 3> _spin{};

PS Example in the doc and internet don't cover delegates in the mvc pattern of Qt framework.

Solution from source code

After studying of qtbase source code test case I found necessary to use QCoreApplication::processEvents() function.

Combobox

Test data

void TestGuiDelegateWithTableView::not_empty_cell2_data()
{
    QTest::addColumn<int>("index");
    QTest::addColumn<QString>("display");
    QTest::addColumn<int>("user");

    QTest::newRow("foo 2") << 0 << "foo" << 2;
    QTest::newRow("bar 4") << 1 << "bar" << 4;
    QTest::newRow("baz 6") << 2 << "baz" << 6;
}

test body

void TestGuiDelegateWithTableView::not_empty_cell2()
{
    QVERIFY2(table, "Should be not empty");
    const auto cell = table->model()->index(0, 0);
    const auto center = table->visualRect(cell).center();

    // begin common trash
    auto* viewport = table->viewport();
    QVERIFY2(viewport, "Should be not empty");
    QTest::mouseClick(viewport, Qt::LeftButton, Qt::KeyboardModifiers(), center);
    QTest::mouseDClick(viewport, Qt::LeftButton, Qt::KeyboardModifiers(), center);
    QVERIFY2(viewport->focusWidget(), "Should be not empty");
    // end common trash

    QFETCH(int, index);
    for (auto i = 0; i < index; ++i) QTest::keyPress(viewport->focusWidget(), Qt::Key_Down);
    QTest::keyPress(viewport->focusWidget(), Qt::Key_Enter);
    QCoreApplication::processEvents(); // <-- here is important

    QFETCH(QString, display);
    QFETCH(int, user);
    const auto actual_display = table->model()->index(0, 0).data(Qt::DisplayRole).toString();
    const auto actual_user = table->model()->index(0, 0).data(Qt::UserRole).toInt();
    QCOMPARE(display, actual_display);
    QCOMPARE(user, actual_user);
}

Spinbox

test data

void TestGuiDelegateWithTableView::spinbox_data()
{
    QTest::addColumn<double>("user_input");
    QTest::newRow("-10.0") << -10.;
    QTest::newRow("+10.0") <<  10.;
    QTest::newRow("0.0")   <<  0.0;
}

test body

void TestGuiDelegateWithTableView::spinbox()
{
    QVERIFY2(table, "Should be not empty");
    QVERIFY2(table->model(), "Should be not empty");

    QFETCH(double , user_input);

    const auto cell = table->model()->index(0, 1);
    const auto center = table->visualRect(cell).center();
    QTest::mouseClick(table->viewport(), Qt::LeftButton, Qt::NoModifier, center);
    QTest::mouseDClick(table->viewport(), Qt::LeftButton, Qt::NoModifier, center);
    QTest::keyClicks(table->viewport()->focusWidget(), QString::number(user_input, 'g', 6));
    QTest::keyPress(table->viewport()->focusWidget(), Qt::Key_Enter);
    QCoreApplication::processEvents(); // here

    const auto actual = table->model()->index(0, 1).data(Qt::DisplayRole).toDouble();
    QVERIFY(qFuzzyCompare(actual, user_input));
}

NB

In the Qt source there is somewhere the following lines:

#if defined(Q_OS_UNIX)
    QCoreApplication::processEvents();
#endif