code: def testBuyAndSellWin(self):
      posTracker = returns.PositionTracker(broker.IntegerTraits())
      posTracker.buy(1, 10)
      self.assertEqual(posTracker.getAvgPrice(), 10)
      posTracker.sell(1, 11)
      self.assertEqual(posTracker.getAvgPrice(), 0)
      self.assertEqual(posTracker.getPnL(), 1)
      self.assertTrue(posTracker.getReturn() == 0.1)
  
imports: import datetime
  from .None import common
  from .None import strategy_test
  from .None import position_test
  from testcases import test_strategy
  from pyalgotrade.barfeed import yahoofeed
  from pyalgotrade.barfeed import csvfeed
  from pyalgotrade.stratanalyzer import returns
  from pyalgotrade import broker
  from pyalgotrade import marketsession
label_desc: Use image node_id 3 for calling the PosTrackerTestCase obj's underlying member method code with example usage: obj.testBuyAndSellWin() without return types