old_contents: import unittest
  from datetime import datetime
  
  from stock import Stock
  
  
  class StockTest(unittest.TestCase):
      def test_new_stock_price(self):
          """A new stock should have a price that is None.
  
          """
          stock = Stock("GOOG")
          self.assertIsNone(stock.price)
  
      def test_stock_update(self):
          """An update should set the price on the stock object.
  
          Notes:
              We will be using the `datetime` module for the timestamp.
          """
          stock = Stock("GOOG")
          stock.update(datetime(2014, 2, 12), price=10)
          self.assertEqual(10, stock.price)
  
      def test_negative_price_exception(self):
          """An update with a negative price should return a value error.
  
          """
          stock = Stock("GOOG")
          self.assertRaises(ValueError, stock.update, datetime(2014, 2, 13), -10)
  
  
  if __name__ == "__main__":
      unittest.main()
  
new_contents: import unittest
  from datetime import datetime
  
  from stock import Stock
  
  
  class StockTest(unittest.TestCase):
      def setUp(self):
          self.stock = Stock("GOOG")
  
      def test_new_stock_price(self):
          """A new stock should have a price that is None.
  
          """
          self.assertIsNone(self.stock.price)
  
      def test_stock_update(self):
          """An update should set the price on the stock object.
  
          Notes:
              We will be using the `datetime` module for the timestamp.
          """
          self.stock.update(datetime(2014, 2, 12), price=10)
          self.assertEqual(10, self.stock.price)
  
      def test_negative_price_exception(self):
          """An update with a negative price should return a value error.
  
          """
          self.assertRaises(ValueError, self.stock.update, datetime(2014, 2, 13), -10)
  
      def test_stock_holds_latest_price(self):
          """A stock should hold the latest price.
  
          Executes five updates.
          """
          self.stock.update(datetime(2014, 2, 12), price=10)
          self.stock.update(datetime(2014, 2, 12), price=10.2)
          self.stock.update(datetime(2014, 2, 12), price=15.789)
          self.stock.update(datetime(2014, 2, 12), price=18.236458)
          self.stock.update(datetime(2014, 2, 12), price=23.12)
          self.assertAlmostEqual(23.12, self.stock.price, places=4)
  
  
  class StockTrendTest(unittest.TestCase):
      def setUp(self):
          self.stock = Stock("GOOG")
  
      def test_increasing_trend_true_3_updates(self):
          """Tests if prices from last three updates are increasing.
  
          Use 3 updates.
          """
          timestamps = [datetime(2014, 2, 11), datetime(2014, 2, 12), datetime(2014, 2, 13)]
          prices = [8, 10, 12]
          for timestamp, price in zip(timestamps, prices):
              self.stock.update(timestamp, price)
          self.assertTrue(self.stock.is_increasing_trend())
  
      def test_increasing_trend_false_3_updates(self):
          """Tests if prices from last three updates are not increasing.
  
          Use 3 updates.
          """
          timestamps = [datetime(2014, 2, 11), datetime(2014, 2, 12), datetime(2014, 2, 13)]
          prices = [10, 8, 12]
          for timestamp, price in zip(timestamps, prices):
              self.stock.update(timestamp, price)
          self.assertFalse(self.stock.is_increasing_trend())
  
      def test_increasing_trend_true_5_mixed_updates(self):
          """Tests if prices from last three updates are increasing.
  
          Use 5 updates with only the last three increasing.
          """
          timestamps = [datetime(2014, 2, 11), datetime(2014, 2, 12), datetime(2014, 2, 13), datetime(2014, 2, 14),
                        datetime(2014, 2, 15)]
          prices = [11, 12, 8, 10, 14]
          for timestamp, price in zip(timestamps, prices):
              self.stock.update(timestamp, price)
          self.assertTrue(self.stock.is_increasing_trend())
  
      def test_increasing_trend_false_5_mixed_updates(self):
          """Tests if prices from last five updates are not increasing.
  
          Use 5 updates with only the first three increasing.
          """
          timestamps = [datetime(2014, 2, 11), datetime(2014, 2, 12), datetime(2014, 2, 13), datetime(2014, 2, 14),
                        datetime(2014, 2, 15)]
          prices = [8, 10, 12, 14, 10, 11]
          for timestamp, price in zip(timestamps, prices):
              self.stock.update(timestamp, price)
          self.assertFalse(self.stock.is_increasing_trend())
  
  if __name__ == "__main__":
      unittest.main()
  
subject: Add StockTrendTest class and increasing trend true and false tests for 3 updates and 5 mixed updates respectively.