018-turtle/docs/milestones/mil-002-square-and-dashed-line.md

Milestone 002: Square and Dashed Line

Metadata

Key	Value
ID	MIL-002
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	pending

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Purpose

This milestone decides whether the first two challenges (Turtle Challenge 1, draw a square, and Turtle Challenge 2, draw a dashed line) work, are tested without a display and can be started from the command line, and whether the turtle abstraction that every later challenge relies on is sound.

Deliverable

The mil-002-square-and-dashed-line branch, opened as one pull request, containing the Pen protocol and window helpers, draw_square, draw_dashed_line, a recording fake turtle for tests, tests for both functions, and the turtle-challenges command with the square and dashed-line challenges.

Go / No-Go Criteria

#	Criterion (objectively checkable)	Go	No-Go
1	draw_square draws four sides of 100 units, turning 90 degrees after each, as shown by the recording fake turtle	The recorded moves match	Any recorded move differs
2	draw_dashed_line draws the configured number of dashes of 10 units, each followed by a gap of 10 units, with the pen down for each dash and up for each gap, and leaves the pen down when it returns	The recorded moves match	Any recorded move differs
3	Every number and name used by the two functions comes from constants.py	No magic number in the function bodies	A literal constant is found in a function body
4	python -m turtle_challenges square and python -m turtle_challenges dashed-line each open a window and draw to completion on Windows PowerShell	S01 confirms both in the review record	Either fails
5	No test opens a window	The test run passes with no display available	A test needs a display
6	python -m pytest, ruff check ., ruff format --check ., mypy and doxygen Doxyfile	All exit 0 with 0 Doxygen warnings	Any fails or warns
7	Review record against QC-PY-001	Verdict Go	Go-with-conditions or No-Go

Dependencies

Depends on	Reason
MIL-001 accepted	Needs the project configuration, package skeleton, test setup and continuous integration

Traceability

Business Case objective / KPI / user story	Reference
Challenges 1 and 2 run	O1 in BC-001
Drawing logic separate from the window	O2 in BC-001
Source documented with Doxygen	O5 in BC-001

Ownership

Role	Stakeholder ID (SA)
Owner	S01
Approving reviewer	S01

Target Date

2026-10-14 — the second milestone, after the foundation milestone of 2026-10-10 and before the plan ends on 2026-10-21 (Constraints in BC-001).

Tasks

#	Task	Summary	Needs its own Use Case/User Story?	Reference
1	Define the Pen protocol and window helpers	Add pen.py with a Pen protocol listing the turtle methods the challenges use, and helpers that create the Screen (color mode 255) and the Turtle named tim. The drawing functions take a Pen, so tests can pass a fake. The Doxygen comments also explain the import styles of the lecture (import turtle, from turtle import Turtle, import turtle as t) and why the wildcard import is avoided.	No
2	Add a recording fake turtle for tests	Add a fake in tests/ that implements the Pen protocol and records every call (move, turn, pen up, pen down, color), so tests assert on the drawing without a window.	No
3	Implement draw_square	Implement draw_square(pen, side_length): four times move forward by the side length (100) and turn right 90 degrees, using a for loop. The default side length is a constant in constants.py.	No
4	Implement draw_dashed_line	Implement draw_dashed_line(pen, dash_count, dash_length): for each dash put the pen down and move forward 10, then put the pen up and move forward 10 for the gap. The number of dashes (50) and the lengths are constants; see the open issue on 50 versus 15 in the Project Plan.	No
5	Add tests for square and dashed line	Test both functions against the recording fake turtle: number of moves, lengths, turn angles, pen up and pen down order, and rejection of a non-positive length.	No
6	Add the command line entry point	Add cli.py with main(argv) and __main__.py so that python -m turtle_challenges <challenge> creates the window, runs the named challenge and waits for a click. Register square and dashed-line; the choices are listed by --help. Declare the turtle-challenges command in pyproject.toml, since it points at cli.py.	No
7	Review milestone 002 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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