# A note about Modal Dialogs

## Simple Dialogs

For QMessageBox.question one approach is to mock the function using the monkeypatch fixture:

    def test_Qt(qtbot, monkeypatch):
        simple = Simple()
        qtbot.addWidget(simple)

        monkeypatch.setattr(QMessageBox, "question", lambda *args: QMessageBox.Yes)
        simple.query()
        assert simple.answer

## Custom Dialogs

Suppose you have a custom dialog that asks the user for their name and age, and a form that uses it. One approach is to add a convenience function that also has the nice benefit of making testing easier, like this:

    class AskNameAndAgeDialog(QDialog):
        @classmethod
        def ask(cls, text, parent):
            dialog = cls(parent)
            dialog.text.setText(text)
            if dialog.exec_() == QDialog.Accepted:
                return dialog.getName(), dialog.getAge()
            else:
                return None, None

This allows clients of the dialog to use it this way:

    name, age = AskNameAndAgeDialog.ask("Enter name and age because of bananas:", parent)
    if name is not None:
        # use name and age for bananas
        ...

And now it is also easy to mock `AskNameAndAgeDialog.ask` when testing the form:

    def test_form_registration(qtbot, monkeypatch):
        user = User.empty_user()
        form = RegistrationForm(user)

        monkeypatch.setattr(
            AskNameAndAgeDialog, "ask", classmethod(lambda *args: ("John", 30))
        )
        # Clicking on the button will call AskNameAndAgeDialog.ask in its slot.
        form.enter_info_button.click()

        assert user.name == "John"
        assert user.age == 30