Software Engineering with Python

Curriculum

1. 01From Script to FunctionsWhy code that works once isn't yet software, how to turn a copy-and-paste script into small functions with clear inputs and outputs, and the first signs that the numbers it produces are wrong.15 min
2. 02Money and RoundingWhy floating-point numbers and Python's round() are wrong for money, how to calculate in whole kobo with Decimal and round half up, and how many of Tallybook's real invoices the old way got wrong.15 min
3. 03Modules and TestsMove the invoice rules into a module, write automated tests for them with pytest, and run the tests in Colab, so every change is checked in seconds instead of by hand.15 min
4. 04Edge Cases and BoundariesDesign tests around boundaries, where most bugs live, use pytest's parametrize to check many cases at once, and find and fix an off-by-one bug in Tallybook's late fees.15 min
5. 05DebuggingRead a traceback from the bottom up, narrow a failure down to the exact input that causes it, and use the data to find every row with the same problem, instead of fixing them one crash at a time.15 min
6. 06Validating InputCheck every record before using it, collect every problem with a clear reason instead of crashing on the first, and decide what happens to bad records so they're fixed rather than silently dropped.25 min
7. 07Version Control with GitTrack every change to code with Git, make small commits with clear messages, work on a branch, read a diff, and merge, all with real commands in Colab.15 min
8. 08Code ReviewReview code for correctness, clarity and risk, use simple automated checks to find common problems, and write review comments that are specific, kind and actionable, on Tallybook's original billing module.25 min
9. 09Building an APIExpose the invoice rules as a small web API with Flask, validate requests and return clear errors with the right status codes, and test the API without running a server.15 min
10. 10Final ProjectPlan your final project, a tested, version-controlled invoicing package and API that replaces the old billing module, with every rule tested at its boundaries and every row of the export accounted for.20 min
11. Final assessmentPass it (60% or more) to earn the Software Engineering with Python course completion badge.