015-coffee_machine/docs/business-case.md

Business Case

Metadata

Key	Value
ID	BC-001
CrossReference	SA-001

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-10-05	Accepted	Jens Tirsvad Nielsen	S01	Initial version	c0c3940

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Executive Summary

Build a console coffee machine in Python as the Day 15 assignment of Udemy's "100 Days of Code: The Complete Python Pro Bootcamp". The program serves espresso, latte and cappuccino, accepts US coins, tracks water, milk and coffee and prints a report on request. It is published as a readable, runnable reference for other course participants and as a portfolio piece.

Methodological and Standards Foundation

Planning follows the SQA/QC framework mounted at framework/ (plan first, then code). Quality is described with ISO/IEC 25010:2023 characteristics. Code uses the coding-conventions skill and Doxygen comments.

Problem Statement

The assignment specification is long and detail-heavy (resources, coins, refunds, change). Solutions shared by participants vary widely in structure and readability, and a single main.py script is hard to test.

Business Opportunity

A small, well-structured and tested solution is a clear example for other participants and for viewers browsing the repository.

Objectives

1. Implement the full assignment behaviour: report, off, drink selection, resource check, coin processing, change, profit.
2. Keep the assignment's function names so participants can compare solutions.
3. Cover the behaviour with automated pytest tests.
4. Document how to set up a local .venv and run the program and tests.
5. Publish the repository with a description, topics and README.

Scope

In Scope

• Console program under src/ with a constants.py for menu, coins and starting resources.
• pytest tests under tests/.
• pyproject.toml, Python .gitignore, Doxyfile, README.md.
• Project documents under docs/.
• Repository description and topics on the git host.

Out of Scope

• Graphical or web interface.
• Payment other than the four US coins.
• Persistence of resources or profit between runs.
• Runtime dependencies.

Expected Benefits

Tangible Benefits

• Completed Day 15 assignment.
• Runnable code with tests and setup instructions.

Intangible Benefits

• Practice with planning, testing and Python project layout.
• A reusable template for later course projects.

Strategic Alignment

Supports the learner's goal of finishing the 100 Days of Code course with professional project hygiene, and the goal of sharing readable solutions.

Success Criteria

#	Criterion	Target	Measure
1	Assignment behaviours implemented	100% of listed behaviours	Manual run against the specification
2	Tests pass	All pytest tests green	python -m pytest
3	Runtime dependencies	0	pyproject.toml dependencies is empty
4	Setup documented	A new reader can run program and tests from README	README walkthrough
5	Repository metadata	Description and at least 3 topics set	Repository page

Risks

Risk	Impact	Mitigation
Floating-point rounding in coin totals	Wrong change or refund	Compute money in cents (integers) internally
Token in .env leaks	Account compromise	.env is gitignored, never imported or tested by the project
Scope creep beyond the assignment	Delay	Out of Scope list above

Assumptions

• Python 3.13 or newer is installed.
• The git host repository already exists and is reachable.

Constraints

• Python greater than 3.13 as requested, venv for environments, pytest for tests.
• Constants live in constants.py.
• Source files use Doxygen comments.
• Nothing is committed or pushed unless the user asks.

Cost–Benefit Assessment

Costs	Benefits
A few hours of the learner's time	Finished, tested, shareable assignment (qualitative; no money involved)

Stakeholders

Stakeholder ID (SA)	Interest in this project
S01	Completes the assignment and owns the plan, code and review
S02	Reads and runs the code, compares solutions
S03	Browses the repository for ideas

Recommendation

Proceed — the scope is small, well specified and delivers a reusable example.

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