HW10-PythonTesting

You have just been hired as a software engineer at a small startup. The company is looking for a talented software engineer to join their team. You are that person! Your boss's first task is to fix bugs in the badcode module: a collection of small functions.

You have been asked to write a test suite for the badcode module to help expose all the bugs by showing test failures. After exposing the bugs you should try and fix any errors. Follow the steps below to get started.

Part 1 (4 points)

1. Create a conda virtual environment called "hw10": conda create -n hw10 python=3.9
2. Activate the virtual environment: conda activate hw10
3. Install the badcode package in "development mode": pip install -e .
4. Run the tests: pytest -v. You should get output like this:

This is showing that there were test failures! I have already written one test for you and it is showing that there are bugs in the badcode module. You should be seeing red until you fix the bugs, which you will do in Part 3. Take a screen shot of this output and save it as part1-2.png in the imgs directory. This is to prove that you successfully completed part 1.

Part 2 - Write tests and show failures (7 points)

1. Look at the badcode module and find the __init__.py file. This file has all the functions you need to write tests for. To know what the function is supposed to do, read the "docstring", which is the text that appears just below the function definition.

For example the badcode.sum_all function has function and docstring:

def sum_all(numbers):
    """
    Add together all the numbers in a list.

    :param numbers: A list of numbers.
    :return: The sum of all the numbers in the list.
    """
    total = 1
    for number in numbers:
        total += number
    return total

You can see that the text explains what the function does. numbers should be a list of numbers and this function adds them all together and returns the total.

2. Tests are written in tests/test_badcode.py file. Look at the test for the badcode.sum_all function that is inside tests/test_badcode.py file. It should be called test_sum_all.

Remember that a test is a function that starts with test_. Here is an example one already created for you. Here is the test for badcode.sum_all function:

def test_sum_all():
    assert sum_all([1, 2, 3]) == 6

Remember that you can also use pytest.mark.parameterize decorate to test different inputs. Here is an example of the @pytest.mark.parametrize decorator to test different inputs.

@pytest.mark.parametrize("numbers, expected", [
    ([1, 2, 3], 6),
    ([1, 2, 3, 4], 10),
    ([1, 2, 3, 4, 5], 15),
])
def test_sum_all(numbers, expected):
    assert sum_all(numbers) == expected

3. Write a test/tests for badcode.multiply_all. You need a minimum of one test.

4. Write a test/tests for badcode.count_characters. You need a minimum of one test.

5. Write a test/tests for badcode.count_words. You need a minimum of one test.

6. Write a test/tests for badcode.count_lines. You need a minimum of one test.

7. Write a test/tests for badcode.greet. You need a minimum of one test.

8. Write a test/tests for badcode.check_is_palindrome. You need a minimum of one test.

9. Run all your tests: pytest. You should get an output of your tests similar to this:

.....MORE CODE ABOVE .......
string = 'roger', expected = False

    @pytest.mark.parametrize("string, expected", [
        ("roger", False),
        ("racecar", True),
        ("madam", True)
    ])
    def test_palindrome(string, expected):
>       assert(check_is_palindrome(string) == expected)
E       AssertionError: assert True == False
E        +  where True = check_is_palindrome('roger')

tests\test_badcode.py:67: AssertionError
=============================================== short test summary info ===============================================
FAILED tests/test_badcode.py::test_sum_all - assert 7 == 6
FAILED tests/test_badcode.py::test_multiply_all[numbers1-24] - assert 0 == 24
FAILED tests/test_badcode.py::test_count_characters[hello-l-2] - AssertionError: assert None == 2
FAILED tests/test_badcode.py::test_count_characters[hello-o-1] - AssertionError: assert None == 1
FAILED tests/test_badcode.py::test_count_characters[hello-g-0] - AssertionError: assert None == 0
FAILED tests/test_badcode.py::test_count_words[hello im hungry\nHow about you?-2] - AssertionError: assert 0 == 2
FAILED tests/test_badcode.py::test_count_words[hello-1] - AssertionError: assert 0 == 1
FAILED tests/test_badcode.py::test_count_words[hello you\nare\nthere-3] - AssertionError: assert 0 == 3
FAILED tests/test_badcode.py::test_greet[Jeremy-Hello, Jeremy!] - AssertionError: assert 'HelloJeremy' == 'Hello, Jer...

FAILED tests/test_badcode.py::test_greet[Roger-Hello, Roger!] - AssertionError: assert 'HelloRoger' == 'Hello, Roger!'
FAILED tests/test_badcode.py::test_palindrome[roger-False] - AssertionError: assert True == False
============================================ 11 failed, 3 passed in 0.14s =============================================

Basically, a bunch of failed tests (maybe some passing). We have now written tests for all the functions in badcode module. Now lets fix them in the next section.

Part 3 - Fix bugs! (7 points)

Now fix all the bugs that were in the functions and discovered by your tests. You can do this by editing the badcode/__init__.py file and fixing each function one by one. After you have fixed a bug in one function, you should see if the test pass when you run pytest -v. It will show passing tests first and then failing tests so you may need to scroll up. If it passes, you are done with that function. If it fails, you should try to fix the bug again in that function and then run pytest -v again.

You have a total of seven functions to fix. After you fix your functions, run pytest -v again and you should get this:

In this example I wrote 17 different tests for all 7 functions. They all passed, I fixed the bugs! Remember, you only need a minimum of one test for each function (7 total).

Resources

Here is a list of resources that may be helpful.

• https://bas.codes/posts/python-pytest-introduction
• https://raphael.codes/blog/customizing-your-pytest-test-suite-part-1/