def test_apply_overwrites_sets_default_for_choice_variable(template_context) -> None:
    """Verify overwritten list member became a default value."""
    generate.apply_overwrites_to_context(
        context=template_context, overwrite_context={'orientation': 'landscape'}
    )

    assert template_context['orientation'] == ['landscape', 'all', 'portrait']
Verify overwritten list member became a default value.
tests/test_generate_context.py