text: import pytest
  from sqlalchemy import create_engine
  
  from relay.blockchain.exchange_proxy import ExchangeProxy
  from relay.exchange.orderbook import OrderBookGreenlet
  
  
  @pytest.fixture()
  def engine():
      return create_engine("sqlite:///:memory:")
  
  
  @pytest.fixture()
  def orderBook(
      engine, web3, exchange_abi, token_abi, testnetworks, is_currency_network_function
  ):
      exchange_address = testnetworks[1].address
      orderBook = OrderBookGreenlet()
      orderBook.connect_db(engine)
  
      orderBook.add_exchange(
          ExchangeProxy(
              web3,
              exchange_abi,
              token_abi,
              exchange_address,
              is_currency_network_function,
          )
      )
  
      return orderBook
  