I719 Fundamentals of Python/lecture2

Lecture 2

Importing from files

• imported files get executed
• python needs a file named __init__.py in the directory ofr the file to import it
• __init__.py gets executed when something within the directory is imported
• to not execute on import, put code within a if statement like:

if __name__ == "__main__":

• For development and debugging, it is very useful to import thing into an interactive python shell

Unittests

import unittest

HELLO_WORLD = 'hello world'

class HelloTests(unittest.TestCase):
    def test_string_correct(self):
        self.assertEqual(HELLO_WORLD, 'hello world')

def main():
    print(HELLO_WORLD)

if __name__ == "__main__":
    main()

Running Unittest

python3 -m unittest helloprinter.py

Task 1

Make FizzBuzz testable Make a function that return Fizz if divisible by 3, buzz if divisible by 5, FizzBuzz if divisible by both 3 and 5, and the returns the number if niether is met. And then write tests for these cases

Solution

import unittest

def fizz_buzz(i):
    if i % 15 == 0:
        return 'FizzBuzz'
    elif i % 3 == 0:
        return 'Fizz'
    elif i % 5 == 0:
        return 'Buzz'
    else:
        return i

if __name__ == "__main__":
    for i in range(1, 101):
        print(fizz_buzz(i))

class FizzBuzzTestCase(unittest.TestCase):
    def test_fizz(self):
        result = fizz_buzz(3)
        self.assertEqual(result, 'Fizz')

    def test_buzz(self):
        result = fizz_buzz(5)
        self.assertEqual(result, 'Buzz')

    def test_fizzbuzz(self):
        result = fizz_buzz(15)
        self.assertEqual(result, 'FizzBuzz')

    def test_niether(self):
        result = fizz_buzz(1)
        self.assertEqual(result, 1)

Dictionary

>>> a = [1, 2, 3]
>>> a[1]
2
>>> a[0]
1
>>> hello = "hello"
>>> hello[1]
'e'
>>> [(1, 'h'), (2, 'e')]
[(1, 'h'), (2, 'e')]
>>> a = [(1, 'h'), (2, 'e')]
>>> example_dict = {'python': 1991}
>>> example_dict
{'python': 1991}
>>> example_dict['python']
1991
>>> example_dict['p']
Traceback (most recent call last):
  File "<input>", line 1, in <module>
    example_dict['p']
KeyError: 'p'
>>> example_dict.get('python')
1991
>>> example_dict.get('pythons')
>>> example_dict.get('pythons', 1990)
1990
>>> example_dict['javascript'] = 1995
>>> example_dict
{'javascript': 1995, 'python': 1991}
>>>