Getting started

• Make a directory ~/cs2613/labs/L17
• Download Work.zip and unzip in your newly created directory.
• Download Part of the textbook solution to Exercise 3.18

Questions

• About the JavaScript Quiz
• About the review session on Tuesday.

Raising exceptions

• Complete Exercise 3.8. This only needs a few lines of code added to your solution to 3.6.

• Question for your journal: where should the added error check go, and why?

• Here we need to do something new, to write a test that checks for an exception

def test_exception():
    with pytest.raises(RuntimeError) as e_info:
        prices = parse_csv('Data/prices.csv', select=['name','price'], has_headers=False)

• Question for your journal: does the exception here need to be RuntimeError? Why or why not?

Modules

• This is a modified version of Exercise 3.12.

• Update your report2.py so that it does not directly import import csv, but rather read_portfolio calls parse_csv from fileparse.py.

• Use an appropriate import statement for parse_csv, do not copy that code into report2.py

• make sure that the existing tests continue to pass, along with the following.

def test_prices():
    portfolio = read_portfolio('Data/portfolio.csv')

    prices = {  s['name']: s['price'] for s in portfolio }
    assert prices['AA'] == pytest.approx(32.2,abs=0.001)
    assert prices['GE'] == pytest.approx(40.37,abs=0.001)

• Question for your journal, what is the name of the feature used to construct prices?

Methods

• Start from the following skeleton class

  class Stock:
    def init(self, name, shares, price):
        self.name=name
        self.shares=shares
        self.price=price

• Complete Exercise 4.2; in particular add methods cost and sell to your Stock class so that the following tests pass.

def test_cost2():
    s = Stock('GOOG', 100, 490.10)
    assert s.cost() == pytest.approx(49010.0,0.001)

def test_sell():
    s = Stock('GOOG', 100, 490.10)
    s.sell(25)
    assert s.shares == 75
    assert s.cost() == pytest.approx(36757.5, 0.001)

Special Methods

• Complete Exercise 4.9. In particular add the appropropriate method to the Stock class so that the following test passes.

def test_repr():
    goog = Stock('GOOG', 100, 490.1)
    assert repr(goog) == "Stock('GOOG', 100, 490.1)"

Before next lab