Exercise 7.1
In this exercise, you will explore the basic mechanics of using
Python’s unittest module.
(a) Preliminaries
In earlier exercises, you wrote a file stock.py that contained a Stock
class. For this exercise, it assumed that you’re using the code written
for Exercise 6.2. If, for some reason, that’s not working,
you might want to copy the solution from Solutions/6_2 to your working
directory.
(b) Writing Unit Tests
In a separate file teststock.py, write a set a unit tests
for the Stock class. To get you started, here is a small
fragment of code that tests instance creation:
# teststock.py
import unittest
import stock
class TestStock(unittest.TestCase):
def test_create(self):
s = stock.Stock('GOOG', 100, 490.1)
self.assertEqual(s.name, 'GOOG')
self.assertEqual(s.shares, 100)
self.assertEqual(s.price, 490.1)
if __name__ == '__main__':
unittest.main()
Run your unit tests. You should get some output that looks like this:
.
----------------------------------------------------------------------
Ran 1 tests in 0.000s
OK
Once you’re satisifed that it works, write additional unit tests that check for the following:
-
Make sure the
s.costproperty returns the correct value (49010.0) -
Make sure the
s.sell()method works correctly. It should return the number of shares remaining and decrement the value ofs.sharesaccordingly. -
Make sure that the
s.sharesattribute can’t be set to a non-integer value.
For the last part, you’re going to need to check that an exception is raised. An easy way to do that is with code like this:
class TestStock(unittest.TestCase):
...
def test_bad_shares(self):
s = stock.Stock('GOOG', 100, 490.1)
with self.assertRaises(TypeError):
s.shares = '100'
(c) Challenge
Write a separate set of unit tests for the read_portfolio() function
in stock.py