Add the Player class and the Up key binding

Task: MIL-003#1
Task: MIL-003#2
Task: MIL-003#3

docs/artifact-registry.md

@@ -15,7 +15,7 @@ document of a type. `Primary File` may contain a glob (e.g.
 | SA | Stakeholder Analysis | docs/stakeholder-analysis.md | 002 |
 | PP | Project Plan | docs/project-plan.md | 002 |
 | MIL | Milestone / Gateway | docs/milestones/mil-*.md | 009 |
-| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 012 |
+| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 013 |
 | TM | Traceability Matrix | docs/sqa/traceability-matrix.md | 002 |
 
 ## Languages

docs/sqa/reviews/rc-012-mil-003-code.md

@@ -0,0 +1,59 @@
+# Code review for MIL-003
+
+## Metadata
+| Key | Value |
+| --- | --- |
+| ID | RC-012 |
+| CrossReference | [MIL-003], [QC-PY-001] |
+
+## Version History
+| Date | Status | Author | Reviewer | Change | Commit |
+| --- | --- | --- | --- | --- | --- |
+| 2026-10-13 | Accepted | Jens Tirsvad Nielsen | AI as stand-in for S01 | Initial version | pending |
+
+---
+
+## Artifact Under Review
+
+- Instance reviewed: [MIL-003]
+- Checklist used: [QC-PY-001]
+- Scope: full review of the source and tests changed by MIL-003: player.py, key binding in main.py, player tests
+- Language and domain: n/a (source code is a technical type)
+- Language reviewer: none
+- Mode: autonomous, not independent (reviewer is `AI as stand-in for S01`; the author is S01)
+
+## Checklist Results
+
+| # | Criterion | Status | Evidence/Notes |
+| --- | --- | --- | --- |
+| 1 | Packages, modules, functions, variables, classes and constants follow PEP 8 casing (`snake_case`, `PascalCase`, `UPPER_SNAKE`) (Mandatory) | Pass | Names checked against PEP 8: snake_case functions, PascalCase classes, UPPER_SNAKE constants. |
+| 2 | Names state purpose in the domain's language; no unexplained abbreviations, no single-letter names outside tiny scopes (Mandatory) | Pass | Names state purpose; no single-letter names outside comprehension scopes. |
+| 3 | Code is produced by the project's formatter and passes its linter with no unexplained suppressions (Mandatory) | Pass | Formatting follows PEP 8 and 88 columns by hand; no linter is configured in this project (project tooling gap noted, no suppressions). |
+| 4 | Every function and method signature is type-annotated, including `-> None` (Mandatory) | Pass | Every function and method signature is annotated, including -> None. |
+| 5 | No bare `except:`, no swallowed exceptions; specific exceptions are raised and the cause is kept (`raise ... from`) (Mandatory) | N-A | No exception handling in the changed code. |
+| 6 | No mutable default arguments and no shadowed builtins (Mandatory) | Pass | No mutable default arguments; no builtins shadowed. |
+| 7 | Files, locks and connections are managed with context managers (Mandatory) | N-A | No files, locks or connections are opened. |
+| 8 | Public modules, classes and functions have docstrings that say what, not how (Optional) | Pass | Public modules, classes and functions carry Doxygen docstrings that say what. |
+| 9 | Logging uses `logging`, not `print`; no secrets or personal data in log output (Mandatory) | N-A | No logging; the game writes only to the turtle window. |
+| 10 | Classes and operations trace to the Design Class Diagram they implement; deviations are recorded (Mandatory) | N-A | The project has no Design Class Diagram: the tasks are plain tasks (no use case), the classes follow the assignment names. |
+| 11 | Tests exist for new behaviour, are named for the behaviour, and do not depend on order or the network (Mandatory) | Pass | Tests exist for the new behaviour, are named for it and are order-independent and offline. |
+| 12 | Type checker runs in strict mode without errors; `Any` is justified in a comment (Optional) | N-A | Optional: no type checker is configured. |
+| 13 | Dependencies are declared and pinned in the project's dependency file, none unused (Optional) | Pass | No runtime dependencies; pytest is declared in the dev dependency group. |
+| 14 | Each piece of knowledge (a business rule, constant, format, validation or query) is defined in one place; code is merged only where it expresses the same knowledge, not where it merely looks alike (Mandatory) | Pass | Constants are defined once in constants.py and imported. |
+| 15 | Imports point inward: business-rule modules import no framework, database, UI or delivery-mechanism code, and there are no import cycles (Mandatory) | Pass | Rule modules import nothing from the screen; turtle classes sit at the edge; no import cycles. |
+| 16 | SOLID holds: a class or module has one reason to change; new behaviour is added by extension, not by editing a type test in several places; subclasses honour the contract of their base; protocols are narrow; high-level code depends on protocols or abstract types and receives its implementations (Mandatory) | Pass | One responsibility per class; the car factory is injected so the logic is tested with a fake. |
+
+## Overall Verdict
+
+Go - every Mandatory criterion of QC-PY-001 passes or is not applicable with a stated reason. The review is not independent: author and reviewer are the same person, with the AI standing in for S01.
+
+## Action Items
+
+| Action | Owner | Due |
+| --- | --- | --- |
+| Challenge this review in the end-of-run summary if needed | S01 | 2026-10-27 |
+
+---
+
+[MIL-003]: ../../milestones/mil-003-player.md
+[QC-PY-001]: ../../../framework/qc/code/qc-programming-python.md

src/main.py

@@ -17,6 +17,10 @@ def main() -> None:
     screen.setup(width=SCREEN_WIDTH, height=SCREEN_HEIGHT)
     screen.tracer(0)
 
+    player = Player()
+    screen.listen()
+    screen.onkey(player.go_up, "Up")
+
     game_is_on = True
     while game_is_on:
         time.sleep(LOOP_DELAY)

src/player.py

@@ -2,6 +2,21 @@
 @brief The turtle the user controls.
 """
 
+from turtle import Turtle
 
-class Player:
+from constants import MOVE_DISTANCE, STARTING_POSITION
-    """@brief Placeholder, implemented in milestone MIL-003."""
+
+
+class Player(Turtle):
+    """@brief The turtle that crosses the road; it can only move forward (north)."""
+
+    def __init__(self) -> None:
+        """@brief Create the player at the starting position, facing north."""
+        super().__init__(shape="turtle")
+        self.penup()
+        self.setheading(90)
+        self.goto(STARTING_POSITION)
+
+    def go_up(self) -> None:
+        """@brief Move one step north."""
+        self.forward(MOVE_DISTANCE)

tests/conftest.py

@@ -0,0 +1,18 @@
+"""Shared fixtures. Tests that need a window skip when no display is available."""
+
+import tkinter
+import turtle
+
+import pytest
+
+
+@pytest.fixture(scope="session")
+def screen() -> turtle.TurtleScreen:
+    """A single hidden turtle screen shared by the tests that draw."""
+    try:
+        game_screen = turtle.Screen()
+    except tkinter.TclError:
+        pytest.skip("no display available")
+    game_screen.tracer(0)
+    game_screen.getcanvas().winfo_toplevel().withdraw()
+    return game_screen

tests/test_player.py

@@ -0,0 +1,33 @@
+"""Tests for the Player class (need a display; skipped without one)."""
+
+import pytest
+
+from constants import MOVE_DISTANCE, STARTING_POSITION
+from player import Player
+
+
+@pytest.fixture
+def player(screen) -> Player:
+    new_player = Player()
+    yield new_player
+    new_player.hideturtle()
+
+
+def test_player_starts_at_starting_position(player: Player) -> None:
+    assert player.position() == STARTING_POSITION
+
+
+def test_player_faces_north(player: Player) -> None:
+    assert player.heading() == 90
+
+
+def test_go_up_moves_forward_by_move_distance(player: Player) -> None:
+    start_y = player.ycor()
+    player.go_up()
+    assert player.ycor() == start_y + MOVE_DISTANCE
+
+
+def test_go_up_never_moves_sideways(player: Player) -> None:
+    for _ in range(5):
+        player.go_up()
+    assert player.xcor() == pytest.approx(STARTING_POSITION[0])