def METHOD_NAME(self):
    """Test with basic data, and empty data"""
    self.send_signal(self.widget.Inputs.topics, self.topics)
    # self.widget.data is transposed, compare accordingly
    self.assertEqual(len(self.topics), len(self.widget.data.domain.variables))
    self.assertEqual(len(self.topics.domain.variables), len(self.widget.data))
    self.send_signal(self.widget.Inputs.topics, None)
    self.assertIsNone(self.widget.data)