018-turtle/docs/milestones/mil-004-random-walk-and-spirograph.md

Milestone 004: Random Walk and Spirograph

Metadata

Key	Value
ID	MIL-004
CrossReference	BC-001
Language	en
Domain	it

Version History

Date	Status	Author	Reviewer	Change	Commit
2026-10-07	Accepted	Jens Tirsvad Nielsen	S01	Initial version	4b3391b

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Purpose

This milestone decides whether the last two challenges (Turtle Challenge 4, generate a random walk, and Turtle Challenge 5, draw a spirograph) work and whether the whole repository is ready to be shared: all five challenges run, the README is complete and checked from a fresh clone, and every success criterion of the Business Case is met.

Deliverable

The mil-004-random-walk-and-spirograph branch, opened as one pull request, containing random_walk, draw_spirograph, their tests, the random-walk and spirograph challenges in the command line, and the final README.md with the Run section for all five challenges.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	random_walk takes the configured number of steps (200), each of the same distance, each in a heading from the north, east, south and west list, and each in an red, green and blue (RGB) color from random_color	Recorded moves match with a seeded generator	Any recorded move differs
2	random_walk sets the pen size and the speed from constants	Both are recorded before the first move	Either is missing
3	draw_spirograph(pen, size_of_gap) draws int(360 / size_of_gap) circles, each in an RGB color, turning the heading by the gap after each circle	Circle count, color and heading changes match	Any differs
4	draw_spirograph rejects a gap that is zero or negative with ValueError and never passes a float to range	The error is raised; a gap of 7 does not raise TypeError	A float reaches range
5	python -m turtle_challenges random-walk and python -m turtle_challenges spirograph open a window and draw to completion on Windows PowerShell	S01 confirms both in the review record	Either fails
6	Business Case success criteria 1 to 7	Every criterion met, evidence in the review record	Any criterion not met
7	A fresh clone follows only the README (set-up, run, test, build the documentation) on Windows PowerShell	Every step works as written	A step fails or is missing
8	python -m pytest, ruff check ., ruff format --check ., mypy and doxygen Doxyfile	All exit 0 with 0 Doxygen warnings	Any fails or warns
9	Review record against QC-PY-001	Verdict Go	Go-with-conditions or No-Go

Dependencies

Depends on	Reason
MIL-003 accepted	Needs random_color and the command line entry point

Traceability

Business Case objective / KPI / user story	Reference
Challenges 4 and 5 run	O1 in BC-001
Set-up and run guide complete	O3 in BC-001
Repository ready to share	O6 in BC-001
Every pull request closes its issues	O7 in BC-001

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-10-21 — the last milestone, on the day the plan ends (Constraints in BC-001).

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Implement random_walk	Implement random_walk(pen, steps, distance, rng): set the pen size and speed, then for each of 200 steps choose a heading from the list of 0, 90, 180 and 270 degrees, give the line a random_color RGB value and move forward by a fixed distance. The directions are a tuple constant.	No
2	Implement draw_spirograph	Implement draw_spirograph(pen, size_of_gap, radius, rng): draw int(360 / size_of_gap) circles, each in a random_color RGB value, and after each circle set the heading to the current heading plus the gap. A zero or negative gap raises ValueError; the int conversion avoids the float error that range raises.	No
3	Add tests for random_walk and draw_spirograph	Test the recorded moves of both functions with a seeded generator and the recording fake turtle: step count, distance, headings drawn from the list, RGB values in range, circle count, heading change and the ValueError for an invalid gap.	No
4	Register random-walk and spirograph in the command line	Add random-walk and spirograph to the choices of python -m turtle_challenges, with a --gap option for the spirograph, and test the argument parsing.	No
5	Complete the README Run section and verify it from a fresh clone	Document the command for each of the five challenges and the --gap option, then follow the README from an empty folder on Windows PowerShell and record the result. Debian and macOS steps are documented but not verified by S01; the README says so.	No
6	Verify the Business Case success criteria	Check each of the seven success criteria of the Business Case, record the evidence (command output, repository page) in the review record, and update the Project Plan if a date moved.	No
7	Review milestone 004 against QC-PY-001	Review the code and tests against QC-PY-001, record the result as an RC-* and update the instance in the traceability matrix.	No

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