05 Team Activity: Testing and Fixing Functions

Instructions

Work as a team as explained in the instructions for the lesson 2 team activity.

Purpose

Writing and running test functions often help a software developer find mistakes in code. During this assignment, you will write three test functions. Then use pytest to run the test functions and use the output of pytest to help you find and fix errors in some program functions.

Problem Statement

Most people around the world today have at least two names, a family name and a given name. In the United States, we usually write a person’s given name followed by his family name. However, when a computer lists names in alphabetical order, it is convenient to list the family name first and then the given name like this:

Toussaint; Marie
Toussaint; Olivier
Washington; George
Washington; Martha

When writing a program that alphabetizes names, it is often helpful to have the following three functions.

make_full_name: Combines a person’s given name and family name into one string with the family name first
extract_family_name: Extracts a person’s family name from his full name
extract_given_name: Extracts a person’s given name from his full name

A programmer has already written those three functions. However, there are mistakes in at least two of the three functions.

Assignment

As a team, write three test functions named test_make_full_name, test_extract_family_name, and test_extract_given_name. Each of the test functions will test one of three previously written program functions. Use pytest to run the test functions and find and fix the mistakes, if any, that are in program functions.

Helpful Documentation

The prepare content for this lesson explains how to use pytest, assert, and approx to automatically verify that functions are correct. It also contains an example test function and links to additional documentation about pytest.
This video about test functions (20 minutes) shows a BYU-Idaho faculty member writing two test functions and using pytest to run them.

Steps

Do the following:

Download the names.py Python file and save it in the same folder where you will save your Python test program. Then open the downloaded file in VS Code. Notice that the downloaded file contains three small functions named: make_full_name, extract_family_name, and extract_given_name. Notice also that each function has a documentation string (a triple quoted string immediately below the function header) that describes what the function does. Read the documentation strings for all three functions. The code in the functions may contain some mistakes.
Using VS Code, open a new Python file and copy and paste the following import statements at the top of the file.
```
from names import make_full_name, \
    extract_family_name, extract_given_name
import pytest
```
Save the file with the name test_names.py in the same folder where you downloaded and saved the names.py file.
In test_names.py, write a function named test_make_full_name that takes no parameters. Write assert statements inside this function to test the value returned from the make_full_name function. If you are not sure what the make_full_name function does or how to test it, read the documentation string that is at the top of the make_full_name function in the names.py file.
In test_names.py write a function named test_extract_family_name that takes no parameters. Write assert statements inside this function to test the value returned from the extract_family_name function.
In test_names.py write a function named test_extract_given_name that takes no parameters. Write assert statements inside this function to test the value returned from the extract_given_name function.

At the bottom of your test_names.py file, write a call to the pytest.main function like this:

# Call the main function that is part of pytest so that the
# computer will execute the test functions in this file.
pytest.main(["-v", "--tb=line", "-rN", __file__])

Save your test_names.py file and run it by clicking the green run icon in VS Code.
Read the output from pytest and use the output to help you find and fix any errors that are in your test functions or the make_full_name, extract_family_name, and extract_given_name functions.
Repeat steps 7 and 8 until you have found and fixed all the mistakes and your three test functions pass.

Core Requirements

Write test_make_full_name so that it tests make_full_name with various names, including long names, short names, and hyphenated names. Fix the mistake in the make_full_name function.
Write test_extract_family_name so that it tests extract_family_name with various names, including long names, short names, and hyphenated names.
Write test_extract_given_name so that it tests extract_given_name with various names, including long names, short names, and hyphenated names. Fix the mistake in the extract_given_name function.

Stretch Challenges

If your team finishes the core requirements in less than an hour, complete one or more of these stretch challenges. Note that the stretch challenges are optional.

In the United States, mailing addresses are supposed to be written
in this form: number street, city, state zipcode
For example: 525 S Center St, Rexburg, ID 83460

Download and save this Python file named address.py. Open a new Python file named test_address.py and write a test function named test_extract_city that verifies that the extract_city function works correctly.
Write a test function named test_extract_state that verifies that the extract_state function works correctly.
Write a test function named test_extract_zipcode that verifies that the extract_zipcode function works correctly.

Testing Procedure

Before you fix the mistakes in the make_full_name and extract_given_name functions, pytest will print output similar to this:

> python test_names.py
===================== test session starts ======================
platform win32--Python 3.8.6, pytest-6.1.2, py-1.9.0, pluggy-0.1
rootdir: C:\Users\cse111\lesson05
collected 3 items

test_names.py::test_make_full_name FAILED                 [ 33%]
test_names.py::test_extract_family_name PASSED            [ 66%]
test_names.py::test_extract_given_name FAILED             [100%]

========================== FAILURES ============================
C:\Users\cse111\early-functions\docs\lesson05\teach_solution.py:
AssertionError: assert 'Smith-Jones;Ava' == 'Smith-Jones; Ava'
C:\Users\cse111\early-functions\docs\lesson05\names.py:31:
ValueError: substring not found
================= 2 failed, 1 passed in 0.14s ==================

After you fix the mistakes in the make_full_name and extract_given_name functions, pytest will print output similar to this:

> python test_names.py
===================== test session starts ======================
platform win32--Python 3.8.6, pytest-6.1.2, py-1.9.0, pluggy-0.1
rootdir: C:\Users\cse111\lesson05
collected 3 items

test_names.py::test_make_full_name PASSED                 [ 33%]
test_names.py::test_extract_family_name PASSED            [ 66%]
test_names.py::test_extract_given_name PASSED             [100%]

====================== 3 passed in 0.12s =======================

Sample Solution

Please work diligently with your team for the one hour meeting. After the meeting is over, please compare your solution to the sample solution and the stretch solution. Please do not look at the sample solutions until you have either finished the program or diligently worked for at least one hour. At the end of the hour, if you are still struggling to complete the assignment, you may use the sample solution to help you finish.

Call Graph

The following call graph shows the function calls and returns in the sample solution for this assignment. From this call graph we see that the computer starts executing the sample test functions by calling the pytest.main function. While executing the pytest.main function, the computer calls the test_make_full_name function which calls the make_full_name function. Then while still executing pytest.main, the computer calls the test_extract_family_name function which calls the extract_family_name function. Then while still executing pytest.main, the computer calls the test_extract_given_name function which calls the extract_given_name function.

Ponder

During this assignment, you downloaded three program functions that work with a person’s name. You wrote three test functions that each test one of the program functions. You used pytest to run your test functions and used the output of pytest to help you find and fix the mistakes in the program functions. How will writing and running test functions help you write better programs?

Submission

When you have finished the activity, please report your progress via the associated I‑Learn quiz. When asked about which of the requirements you completed, feel free to include any work done during the team meeting or after the meeting, including work done with the help of the sample solution, if necessary. In short, report on what you were able to accomplish, regardless of when you completed it or if you needed help from the sample solution.