code: def test_constant_filled_per_tick(self):
      filled_per_tick = 1
      model = TestingSlippage(filled_per_tick)
      order = self.make_order(100)
  
      price, volume = model.process_order(self.bar_data, order)
  
      self.assertEqual(price, self.EQUITY_MINUTE_CONSTANT_CLOSE)
      self.assertEqual(volume, filled_per_tick)
  
imports: from itertools import product
  from unittest import TestCase
  from numpy import array, empty
  from zipline._protocol import BarData
  from zipline.finance.asset_restrictions import NoRestrictions
  from zipline.finance.order import Order
  from zipline.testing import check_arrays, make_alternating_boolean_array, make_cascading_boolean_array, parameter_space
  from zipline.testing.fixtures import WithConstantEquityMinuteBarData, WithDataPortal, ZiplineTestCase
  from zipline.testing.slippage import TestingSlippage
  from zipline.testing.predicates import wildcard, instance_of
  from zipline.utils.numpy_utils import bool_dtype
label_desc: Use image node_id 4 for calling the TestTestingSlippage obj's underlying member method code with example usage: obj.test_constant_filled_per_tick() without return types