def METHOD_NAME(self):
    class NullBoolModel(models.Model):
        field = models.NullBooleanField()
        class Meta:
            app_label = "django_tables2_test"
    class Table(tables.Table):
        class Meta:
            model = NullBoolModel
    column = Table.base_columns["field"]
    self.assertEqual(type(column), tables.BooleanColumn)
    self.assertNotEqual(column.empty_values, ())