def METHOD_NAME(self):
    opts = Options()
    assert len(opts.preferences) == 0
    assert isinstance(opts.preferences, dict)
    opts.set_preference("spam", "ham")
    assert len(opts.preferences) == 1
    opts.set_preference("eggs", True)
    assert len(opts.preferences) == 2
    opts.set_preference("spam", "spam")
    assert len(opts.preferences) == 2
    assert opts.preferences == {"spam": "spam", "eggs": True}