def test_environment_invalid_volume_size(self):
        options = BenchmarkOptions()
        options.parseOptions([])
        self.environ['FLOCKER_ACCEPTANCE_DEFAULT_VOLUME_SIZE'] = 'A'
        with capture_stderr() as captured_stderr:
            exception = self.assertRaises(
                SystemExit,
                get_cluster, options, self.environ,
            )
            self.assertIn(
                'FLOCKER_ACCEPTANCE_DEFAULT_VOLUME_SIZE', exception.args[0]
            )
            self.assertIn(options.getUsage(), captured_stderr())
Returns the valid quantity based on the product's type of
dataset/ETHPy150Open ClusterHQ/flocker/benchmark/test/test_script.py/ClusterConfigurationTests.test_environment_invalid_volume_size--crossover with--dataset/ETHPy150Open diefenbach/django-lfs/lfs/catalog/models.py/Product.get_clean_quantity_value