code: def test_proportion_order_init(mock_exchange_class):
      exchange = mock_exchange_class.return_value
      exchange.options = ExchangeOptions()
      exchange.id = "fake_id"
      exchange.name = "fake_exchange"
  
      wallet_usd = Wallet(exchange, 10000 * USD)
      wallet_btc = Wallet(exchange, 0 * BTC)
      portfolio = Portfolio(USD, [wallet_usd, wallet_btc])
  
      order = proportion_order(
          portfolio=portfolio,
          source=wallet_usd,
          target=wallet_btc,
          proportion=1.0,
      )
  
      assert order
  
imports: import unittest.mock
  from tensortrade.oms.exchanges import ExchangeOptions
  from tensortrade.oms.instruments import USD, BTC
  from tensortrade.oms.orders.create import proportion_order
  from tensortrade.oms.wallets import Wallet, Portfolio
label_desc: Use image node_id 1 for calling a global function with example usage: test_proportion_order_init(mock_exchange_class) without return types