tdd_student_workflow

The idea of this repo is to show the possible workflow that I would follow when having students working through exercises in Python.

We can use pytest to test the different exercises and both black and flake8 to format and lint possible stylistic mistakes.

To start, install the dependencies on a local environment:

python -m venv .env

Activate the environment:

. .env/bin/activate

Install the dependencies:

pip install pytest black flake8

Students should follow a Test Driven Development (TDD) approach when working with this repo. The students receive an empty ejer_template.py file with the function signatures that we use on the tests. Currently, just with the ejer_template.py and the test_ejer_template.py files, there shouldn’t be any syntax errors.

The student working on the exercises would then run pytest to see their progress:

pytest -v

If no functions have been implemented, the student is met with something like:

❯ pytest -v test_ejer_template.py
================================== test session starts ===================================
platform darwin -- Python 3.10.8, pytest-7.2.1, pluggy-1.0.0 -- /private/tmp/python-dir/.env/bin/python
cachedir: .pytest_cache
rootdir: /private/tmp/python-dir
collected 5 items

test_ejer_template.py::test_suma_n_primeros FAILED                                 [ 20%]
test_ejer_template.py::test_tabla_del_n FAILED                                     [ 40%]
test_ejer_template.py::test_es_primo FAILED                                        [ 60%]
test_ejer_template.py::test_primos_inferiores FAILED                               [ 80%]
test_ejer_template.py::test_esperanza_de_vida FAILED                               [100%]

...

================================ short test summary info =================================
FAILED test_ejer_template.py::test_suma_n_primeros - assert [0, 4.0, 2.66...6666666666667] == [0, 0, 0, 0]
FAILED test_ejer_template.py::test_tabla_del_n - AssertionError: assert [[0], [0, 1],..., 0, 0, 0, 0]] == [[], [], [], [], [], []]
FAILED test_ejer_template.py::test_es_primo - assert [False, False...e, False, ...] == [False, False...e, False, ...]
FAILED test_ejer_template.py::test_primos_inferiores - assert [[], [], [], ... [2, 3, 5, 7]] == [[], [], [], [], [], []]
FAILED test_ejer_template.py::test_esperanza_de_vida - AssertionError: assert [{'a': 51, 'b... 'c': 78}, {}] == [{}, {}, {}]
=================================== 5 failed in 0.02s ====================================

This means that basically we are expecting certain scenarios to be met when the exercise is sent to the professor for review. Tests should be exhaustive and cover all the edge cases that we expect. This process for the professor is also beneficial, since it removes possible bugs with the scenarios sent to the students to work on.

Once functions are implemented, the student keeps running pytest -v and they would know all functions are correct (grade feedback) when running the same command outputs:

❯ pytest -v test_ejercicios_introduccion.py
================================== test session starts ===================================
platform darwin -- Python 3.10.8, pytest-7.2.1, pluggy-1.0.0 -- /private/tmp/python-dir/.env/bin/python
cachedir: .pytest_cache
rootdir: /private/tmp/python-dir
collected 5 items

test_ejercicios_introduccion.py::test_suma_n_primeros PASSED                       [ 20%]
test_ejercicios_introduccion.py::test_tabla_del_n PASSED                           [ 40%]
test_ejercicios_introduccion.py::test_es_primo PASSED                              [ 60%]
test_ejercicios_introduccion.py::test_primos_inferiores PASSED                     [ 80%]
test_ejercicios_introduccion.py::test_esperanza_de_vida PASSED                     [100%]

=================================== 5 passed in 0.01s ====================================

🎉 Finally, before sending the code for review, the student runs ./lint.sh ., which in the background is running black and flake8 to ensure certain style conventions are met. Here’s a sample output:

❯ ./lint.sh test_ejercicios_introduccion.py ejercicios_introduccion.py
All done! ✨ 🍰 ✨
2 files left unchanged.
ejercicios_introduccion.py:50:80: E501 line too long (84 > 79 characters)

The files are first formatted with the black formatter and then linted using flake8. The 2 files left unchanged line means that the files are following black’s style rules, while the last line on the snipped is flake8 giving feedback on style aspects that the files can improve. If we fix the issue, we see the following output, with no warnings from flake8:

❯ ./lint.sh test_ejercicios_introduccion.py ejercicios_introduccion.py
All done! ✨ 🍰 ✨
2 files left unchanged.