def _test_success_flush():
            builder = SmallBodiesFileBuilder(self.FILEPATH)
            builder.create_small_body_file()
            builder.add_body(1, [1., 2., 3., 4., 5., 6., 7.])
            builder.flush()

            with open(self.FILEPATH) as f:
                total_lines_count = sum(1 for _ in f)
                self.assertEqual(total_lines_count, 7)

            os.remove(self.FILEPATH)
 def _test_file_existance():
     builder = SmallBodiesFileBuilder(self.FILEPATH)
     builder.add_body(1, [1., 2., 3., 4., 5., 6., 7.])
     with self.assertRaises(FileNotFoundError):
         builder.flush()