Solutions - Chapter 11
11-1: City, Country
Write a function that accepts two parameters: a city name and a country name. The function should return a single string of the form City, Country, such as Santiago, Chile. Store the function in a module called city_functions.py, and save this file in a new folder so pytest won’t try to run the tests we’ve already written.
Create a file called test_cities.py that tests the function you just wrote. Write a function called test_city_country() to verify that calling your function with values such as 'santiago' and 'chile' results in the correct string. Run the test, and make sure test_city_country() passes.
"""A collection of functions for working with cities."""
def city_country(city, country):
"""Return a string like 'Santiago, Chile'."""
return f"{city.title()}, {country.title()}"
Note: This is the same function we wrote in Exercise 8-6.
from city_functions import city_country
def test_city_country():
"""Does a simple city and country pair work?"""
santiago_chile = city_country('santiago', 'chile')
assert santiago_chile == 'Santiago, Chile'
city_country $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/city_country
collected 1 item
test_cities.py . [100%]
============================= 1 passed in 0.01s ==============================
11-2: Population
Modify your function so it requires a third parameter, population. It should now return a single string of the form City, Country - population xxx, such as Santiago, Chile - population 5000000. Run test_cities.py again. Make sure test_city_country() fails this time.
Modify the function so the population parameter is optional. Run the test, and make sure test_city_country() passes again.
Write a second test called test_city_country_population() that verifies you can call your function with the values 'santiago', 'chile', and 'population=5000000'. Run the tests one more time, and make sure this new test passes.
"""A collection of functions for working with cities."""
def city_country(city, country, population):
"""Return a string like 'Santiago, Chile - population 5000000'."""
output_string = f"{city.title()}, {country.title()}"
output_string += f" -population {population}"
return output_string
population $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/population
collected 1 item
test_cities.py F [100%]
================================== FAILURES ==================================
_____________________________ test_city_country ______________________________
def test_city_country():
"""Does a simple city and country pair work?"""
> santiago_chile = city_country('santiago', 'chile')
E TypeError: city_country() missing 1 required positional argument: 'population'
test_cities.py:5: TypeError
========================== short test summary info ===========================
FAILED test_cities.py::test_city_country - TypeError: city_country() missin...
============================= 1 failed in 0.09s ==============================
"""A collection of functions for working with cities."""
def city_country(city, country, population=0):
"""Return a string representing a city-country pair."""
output_string = f"{city.title()}, {country.title()}"
if population:
output_string += f" - population {population}"
return output_string
population $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/population
collected 1 item
test_cities.py . [100%]
============================= 1 passed in 0.01s ==============================
from city_functions_pop_optional import city_country
def test_city_country():
"""Does a simple city and country pair work?"""
santiago_chile = city_country('santiago', 'chile')
assert santiago_chile == 'Santiago, Chile'
def test_city_country_population():
"""Can I include a population argument?"""
santiago_chile = city_country('santiago', 'chile', population=5_000_000)
assert santiago_chile == 'Santiago, Chile - population 5000000'
Note: I have two versions of the city_functions.py module saved in the solution files, so the import statement here has changed to use the updated version of the function.
population $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/population
collected 2 items
test_cities.py .. [100%]
============================= 2 passed in 0.01s ==============================
11-3: Employee
Write a class called Employee. The __init__() method should take in a first name, a last name, and an annual salary, and store each of these as attributes. Write a method called give_raise() that adds $5000 to the annual salary by default but also accepts a different raise amount.
Write a test file for Employee with two test functions, test_give_default_raise() and test_give_custom_raise(). Write your tests once without using a fixture, and make sure they both pass. Then write a fixture so you don’t have to create a new employee instance in each test function. Run the tests again, and make sure both tests still pass.
class Employee:
"""A class to represent an employee."""
def __init__(self, f_name, l_name, salary):
"""Initialize the employee."""
self.first = f_name.title()
self.last = l_name.title()
self.salary = salary
def give_raise(self, amount=5000):
"""Give the employee a raise."""
self.salary += amount
from employee import Employee
def test_give_default_raise():
"""Test that a default raise works correctly."""
employee = Employee('eric', 'matthes', 65_000)
employee.give_raise()
assert employee.salary == 70_000
def test_give_custom_raise():
"""Test that a custom raise works correctly."""
employee = Employee('eric', 'matthes', 65_000)
employee.give_raise(10000)
assert employee.salary == 75_000
employee $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/employee
collected 2 items
test_employee.py .. [100%]
============================= 2 passed in 0.01s ==============================
class Employee:
"""A class to represent an employee."""
def __init__(self, f_name, l_name, salary):
"""Initialize the employee."""
self.first = f_name.title()
self.last = l_name.title()
self.salary = salary
def give_raise(self, amount=5000):
"""Give the employee a raise."""
self.salary += amount
import pytest
from employee import Employee
@pytest.fixture
def employee():
"""An Employee object that will be available to all test functions."""
employee = Employee('eric', 'matthes', 65_000)
return employee
def test_give_default_raise(employee):
"""Test that a default raise works correctly."""
employee.give_raise()
assert employee.salary == 70_000
def test_give_custom_raise(employee):
"""Test that a custom raise works correctly."""
employee.give_raise(10000)
assert employee.salary == 75_000
employee_with_fixture $ pytest
============================ test session starts =============================
platform darwin -- Python 3.10.0, pytest-7.1.2, pluggy-1.0.0
rootdir: /.../solution_files/chapter_11/employee_with_fixture
collected 2 items
test_employee.py .. [100%]
============================= 2 passed in 0.01s ==============================