Merge pull request 'MIL-003: Continuous play and high score' (#37) from mil-003-continuous-play-and-high-score into main

README.md

@@ -19,11 +19,12 @@ This repository continues
 and starts from its finished game; `docs/project-plan.md` tells how the work is
 split into milestones.
 
-> **Status:** in progress. The finished game of day 21 is adopted and runs: the
-> snake moves, eats and grows, the score is shown and the game ends at the wall
-> or at the tail. Continuous play and the high score (milestone 3), the high
-> score file (milestone 4) and the wiki (milestone 5) follow. The sections below
-> describe the game as it is now; they are updated in each milestone.
+> **Status:** in progress. The game of day 21 is adopted and now follows the
+> day-24 lectures on continuous play: the scoreboard shows the score and the high
+> score, and a collision resets the snake and the score instead of ending the
+> game. The high score is kept in memory only; the high score file (milestone 4)
+> and the wiki (milestone 5) follow. The sections below describe the game as it
+> is now; they are updated in each milestone.
 
 ## Requirements
 
@@ -104,11 +105,16 @@ closer to it than 15 pixels the snake eats it: the food moves to a new random
 place, the snake grows by one segment, and the score at the top of the window
 goes up by 1.
 
-The game is over when the head passes the wall (more than 280 pixels from the
-centre on any side) or touches the tail. The snake stops, `GAME OVER` appears in
-the middle of the window, and a click on the window closes it. You can also close
-the window with its close button at any time. (Milestone 3 replaces this with
-continuous play and a high score.)
+The scoreboard at the top of the window reads `Score: 0 High Score: 0`. The score
+counts the foods eaten since the last reset; the high score is the best score so
+far.
+
+The game does not end. When the head passes the wall (more than 280 pixels from
+the centre on any side) or touches the tail, the old snake is sent off the
+screen, a new snake of three segments appears in the middle, the score goes back
+to 0, and the high score is raised if the score was higher. Close the window with
+its close button when you have had enough. The high score is lost when the game
+is closed until milestone 4 stores it in a file.
 
 ## Run the tests
 

docs/artifact-registry.md

@@ -16,7 +16,7 @@ document of a type. `Primary File` may contain a glob (e.g.
 | PP | Project Plan | docs/project-plan.md | 002 |
 | MIL | Milestone / Gateway | docs/milestones/*.md | 006 |
 | DICT | Domain Dictionary | docs/dictionary.md | 002 |
-| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 011 |
+| RC | SQA Review Record | docs/sqa/reviews/rc-*.md | 012 |
 
 ## Languages
 

docs/sqa/reviews/rc-011-mil-003-code.md

@@ -0,0 +1,60 @@
+# RC-011: Code review of MIL-003 (continuous play and high score)
+
+## Metadata
+| Key | Value |
+| --- | --- |
+| ID | RC-011 |
+| CrossReference | [MIL-003], [QC-PY-001] |
+
+## Version History
+| Date | Status | Author | Reviewer | Change | Commit |
+| --- | --- | --- | --- | --- | --- |
+| 2026-10-13 | Proposed | Jens Tirsvad Nielsen | AI as stand-in for S01 | Initial version | [8c81988] |
+
+---
+
+## Artifact Under Review
+
+- Instance reviewed: the source and tests that [MIL-003] delivers (continuous play and high score)
+- Checklist used: [QC-PY-001]
+- Scope: full review of the files changed on the branch of the milestone
+- Language and domain: n/a
+- Language reviewer: none
+- Mode: autonomous, not independent (the reviewer is `AI as stand-in for S01`; the assistant also wrote the code)
+
+## Checklist Results
+
+| # | Criterion | Status | Evidence/Notes |
+| --- | --- | --- | --- |
+| 1 | Packages, modules, functions, variables, classes and constants follow PEP 8 casing (`snake_case`, `PascalCase`, `UPPER_SNAKE`) | Pass | `Snake.reset`, `Scoreboard.reset`, `reset_if_collision`, `high_score` and `SEGMENT_PARKING_POSITION` follow PEP 8; `reset` and `high_score` are the lecture's names. |
+| 2 | Names state purpose in the domain's language; no unexplained abbreviations, no single-letter names outside tiny scopes | Pass | Names state purpose; `HIGH_SCORE_LABEL` and `SEGMENT_PARKING_POSITION` say what they hold. |
+| 3 | Code is produced by the project's formatter and passes its linter with no unexplained suppressions | Pass | `ruff check` and `ruff format --check` exit 0; no `noqa`. |
+| 4 | Every function and method signature is type-annotated, including `-> None` | Pass | `mypy` strict reports no issues in 13 files; every new def is annotated with `-> None` or `-> bool`. |
+| 5 | No bare `except:`, no swallowed exceptions; specific exceptions are raised and the cause is kept (`raise ... from`) | Pass | No exception handling was added; the one handler in `main.main` is unchanged. |
+| 6 | No mutable default arguments and no shadowed builtins | Pass | No mutable default argument; no shadowed builtin. |
+| 7 | Files, locks and connections are managed with context managers | N-A | No file is opened in this milestone (MIL-004). |
+| 8 | Public modules, classes and functions have docstrings that say what, not how | Pass | `reset`, `reset_if_collision` and the new constants have Doxygen comments; `doxygen Doxyfile` ends with 0 warnings. |
+| 9 | Logging uses `logging`, not `print`; no secrets or personal data in log output | Pass | No `print` and no logging. |
+| 10 | Classes and operations trace to the Design Class Diagram they implement; deviations are recorded | Pass | No Design Class Diagram exists (deviation recorded in RC-010 and the pull request); the change adds `reset` to the base classes as the lecture does. |
+| 11 | Tests exist for new behaviour, are named for the behaviour, and do not depend on order or the network | Pass | 149 tests run without a display; new tests cover higher, equal and lower score on `reset`, the parking of old segments, the new head, the forgotten direction, and `main` going on after the wall and the tail. |
+| 12 | Type checker runs in strict mode without errors; `Any` is justified in a comment | Pass | `strict = true`; `ScoreboardLike` stays a narrow protocol (`increase_score`, `reset`); no `Any`. |
+| 13 | Dependencies are declared and pinned in the project's dependency file, none unused | Pass | `dependencies = []` is unchanged. |
+| 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 | Pass | The label, the parking place and the other values are defined once in `constants.py`; `GAME_OVER_*` is removed, not duplicated. |
+| 15 | Imports point inward: business-rule modules import no framework, database, UI or delivery-mechanism code, and there are no import cycles | Pass | `snake.py` and `main.py` still import no `turtle` or `tkinter` at module level (tested); no import cycle. |
+| 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 | Pass | `Snake.reset` reuses `create_snake`, so the starting positions are one piece of knowledge; `main` depends on the `ScoreboardLike` protocol. |
+
+## Overall Verdict
+
+Go — all Mandatory criteria pass or are not applicable. Assessed on 2026-10-13 by the assistant that wrote the code, as stand-in for S01 in autonomous mode. Mode: autonomous, not independent. The pull request is the second look.
+
+## Action Items
+
+| Action | Owner | Due |
+| --- | --- | --- |
+| Challenge this `Go` in the run summary or on the pull request if the stand-in decision is not wanted | S01 | 2026-10-20 |
+
+---
+
+[MIL-003]: ../../milestones/mil-003-continuous-play-and-high-score.md
+[QC-PY-001]: ../../../framework/qc/code/qc-programming-python.md
+[8c81988]: https://git.tirsystem.com/Tirsvad-Udemy-100-days-of-code/024-snake/commit/8c8198827bfc69c75a4f8ff8a393376d073e94c1

src/snake_game/constants.py

@@ -117,8 +117,14 @@ SCOREBOARD_FONT: Final[tuple[str, int, str]] = ("Arial", 24, "normal")
 ## @brief The head touches the tail when it is closer to a segment than this, in pixels.
 TAIL_COLLISION_DISTANCE: Final[int] = 10
 
-## @brief Text shown when the game is over.
-GAME_OVER_TEXT: Final[str] = "GAME OVER"
+## @brief Text in front of the high score on the scoreboard.
+#
+#  The scoreboard writes `Score: <score> High Score: <high_score>`: the score
+#  label, the score, a space, this label and the high score.
+HIGH_SCORE_LABEL: Final[str] = "High Score: "
 
-## @brief Where the game-over text is written: the centre of the screen.
-GAME_OVER_POSITION: Final[tuple[int, int]] = (0, 0)
+## @brief Where a segment of the old snake is sent when the snake is reset.
+#
+#  The place is far outside the 600 by 600 screen, so the old segments are out
+#  of sight, as the day-24 lecture does it.
+SEGMENT_PARKING_POSITION: Final[tuple[int, int]] = (1000, 1000)

src/snake_game/main.py

@@ -3,8 +3,8 @@
 
 The flow follows the lectures "Screen Setup and Creating a Snake Body",
 "Animating the Snake Segments on Screen" and "Controlling the Snake with
-Keypresses", and the day-21 steps in which the snake eats food, the score rises and
-the game ends.
+Keypresses", the day-21 steps in which the snake eats food and the score rises,
+and the day-24 steps in which a collision resets the game and it goes on.
 """
 
 import time
@@ -102,7 +102,7 @@ class FoodLike(Protocol):
 
 
 class ScoreboardLike(Protocol):
-    """! @brief What the eating and game-over checks need from the scoreboard.
+    """! @brief What the eating and reset checks need from the scoreboard.
 
     A `Scoreboard` fits this description, and so does a fake in a test.
     """
@@ -111,8 +111,8 @@ class ScoreboardLike(Protocol):
         """! @brief Add 1 to the score and write it."""
         ...
 
-    def game_over(self) -> None:
-        """! @brief Write the game-over text."""
+    def reset(self) -> None:
+        """! @brief Keep the best score and start the score again at 0."""
         ...
 
 
@@ -190,17 +190,19 @@ def eat_food_if_close(snake: Snake, food: FoodLike, scoreboard: ScoreboardLike)
         scoreboard.increase_score()
 
 
-def end_game_if_over(snake: Snake, scoreboard: ScoreboardLike) -> bool:
-    """! @brief End the game when the head passes the wall or touches the tail.
+def reset_if_collision(snake: Snake, scoreboard: ScoreboardLike) -> bool:
+    """! @brief Start again when the head passes the wall or touches the tail.
 
-    When the game is over the scoreboard writes the game-over text.
+    The game does not end: the scoreboard keeps the best score and starts the
+    score again, and the snake is made again at the starting positions.
 
     @param snake The snake.
-    @param scoreboard The scoreboard that writes the game-over text.
-    @return True when the game is over.
+    @param scoreboard The scoreboard that keeps the high score.
+    @return True when the snake and the score were reset.
     """
     if snake.hits_wall() or snake.hits_tail():
-        scoreboard.game_over()
+        scoreboard.reset()
+        snake.reset()
         return True
     return False
 
@@ -212,9 +214,8 @@ def main() -> None:
     `tkinter.TclError` ("invalid command name"), and `turtle` raises
     `turtle.Terminator` in some other calls once its window is gone. Both mean
     "the player closed the window", so the game ends quietly with exit code 0.
-    When the snake passes the wall or touches its tail the loop ends, the screen is
-    updated so that the game-over text shows, and `screen.exitonclick()` waits for a
-    click.
+    When the snake passes the wall or touches its tail the score and the snake are
+    reset and the game goes on, so the loop runs until the window is closed.
 
     `turtle` and `tkinter` are imported here and not at the top of the module, and
     so are `food` and `scoreboard`, whose classes inherit from `Turtle`: importing
@@ -240,9 +241,6 @@ def main() -> None:
         while game_is_on:
             play_frame(screen, snake)
             eat_food_if_close(snake, food, scoreboard)
-            if end_game_if_over(snake, scoreboard):
-                game_is_on = False
-        screen.update()
-        screen.exitonclick()
+            reset_if_collision(snake, scoreboard)
     except (Terminator, TclError):
         return  # the window was closed: there is nothing left to do

src/snake_game/scoreboard.py

@@ -10,8 +10,7 @@ module first.
 from turtle import Turtle
 
 from snake_game.constants import (
-    GAME_OVER_POSITION,
-    GAME_OVER_TEXT,
+    HIGH_SCORE_LABEL,
     SCORE_LABEL,
     SCOREBOARD_ALIGNMENT,
     SCOREBOARD_COLOR,
@@ -26,8 +25,10 @@ class Scoreboard(Turtle):
     def __init__(self) -> None:
         """! @brief Set the scoreboard up and write the score 0."""
         super().__init__()
-        ## @brief The number of foods the snake has eaten in this game.
+        ## @brief The number of foods the snake has eaten since the last reset.
         self.score = 0
+        ## @brief The largest score reached so far.
+        self.high_score = 0
         self.color(SCOREBOARD_COLOR)
         self.penup()
         self.hideturtle()
@@ -35,10 +36,10 @@ class Scoreboard(Turtle):
         self.update_scoreboard()
 
     def update_scoreboard(self) -> None:
-        """! @brief Wipe the old text and write the label and the score."""
+        """! @brief Wipe the old text and write the score and the high score."""
         self.clear()
         self.write(
-            f"{SCORE_LABEL}{self.score}",
+            f"{SCORE_LABEL}{self.score} {HIGH_SCORE_LABEL}{self.high_score}",
             align=SCOREBOARD_ALIGNMENT,
             font=SCOREBOARD_FONT,
         )
@@ -48,11 +49,13 @@ class Scoreboard(Turtle):
         self.score += 1
         self.update_scoreboard()
 
-    def game_over(self) -> None:
-        """! @brief Write the game-over text at the centre of the screen.
+    def reset(self) -> None:
+        """! @brief Keep the best score, start a new game and write the scoreboard.
 
-        The score stays where it is: the old text is not wiped. Automatic drawing is
-        off in the game, so the screen must be updated after this call.
+        When the score is higher than the high score, it becomes the new high
+        score. The score then goes back to 0.
         """
-        self.goto(GAME_OVER_POSITION)
-        self.write(GAME_OVER_TEXT, align=SCOREBOARD_ALIGNMENT, font=SCOREBOARD_FONT)
+        if self.score > self.high_score:
+            self.high_score = self.score
+        self.score = 0
+        self.update_scoreboard()

src/snake_game/snake.py

@@ -3,9 +3,10 @@
 
 The class follows the lectures "Create a Snake Class & Move to OOP", "Animating
 the Snake Segments on Screen" and "Controlling the Snake with Keypresses", and
-the day-21 steps in which the snake grows and the game ends. It keeps the lectures'
+the day-21 steps in which the snake grows, and the day-24 step in which it is reset
+after a collision. It keeps the lectures'
 names: `Snake`, `segments`, `create_snake`, `add_segment`, `extend`, `move`, `head`,
-`up`, `down`, `left` and `right`. The only differences are that the snake gets
+`reset`, `up`, `down`, `left` and `right`. The only differences are that the snake gets
 the function that makes a segment as a parameter, so that a test can pass a fake
 and needs no window, and how a reversal is refused (see Snake).
 """
@@ -20,6 +21,7 @@ from snake_game.constants import (
     LEFT,
     MOVE_DISTANCE,
     RIGHT,
+    SEGMENT_PARKING_POSITION,
     SEGMENT_SHAPE,
     STARTING_POSITIONS,
     TAIL_COLLISION_DISTANCE,
@@ -204,6 +206,20 @@ class Snake:
         self.head.forward(MOVE_DISTANCE)
         self._direction_of_travel = self.head.heading()
 
+    def reset(self) -> None:
+        """! @brief Start again with a new snake of three segments.
+
+        Every old segment is sent far outside the screen, so it can no longer be
+        seen, the list is emptied, and the snake is created again at the starting
+        positions. The new head is the first new segment, and it points right.
+        """
+        for segment in self.segments:
+            segment.goto(*SEGMENT_PARKING_POSITION)
+        self.segments.clear()
+        self.create_snake()
+        self.head = self.segments[0]
+        self._direction_of_travel = self.head.heading()
+
     def hits_wall(self) -> bool:
         """! @brief Tell whether the head has passed the wall on any side.
 

tests/fakes.py

@@ -138,13 +138,13 @@ class FakeScoreboard:
 
     def __init__(self) -> None:
         self.increases = 0
-        self.game_overs = 0
+        self.resets = 0
 
     def increase_score(self) -> None:
         self.increases += 1
 
-    def game_over(self) -> None:
-        self.game_overs += 1
+    def reset(self) -> None:
+        self.resets += 1
 
 
 class FakeScreen:

tests/test_constants.py

@@ -154,10 +154,18 @@ def test_tail_is_touched_closer_than_10_pixels_which_is_less_than_a_move() -> No
     assert 0 < constants.TAIL_COLLISION_DISTANCE < constants.MOVE_DISTANCE
 
 
-def test_game_over_text_is_written_at_the_centre_inside_the_wall() -> None:
-    x, y = constants.GAME_OVER_POSITION
+def test_game_over_constants_no_longer_exist() -> None:
+    assert not hasattr(constants, "GAME_OVER_TEXT")
+    assert not hasattr(constants, "GAME_OVER_POSITION")
 
-    assert constants.GAME_OVER_TEXT == "GAME OVER"
-    assert (x, y) == (0, 0)
-    assert abs(x) < constants.WALL_LIMIT
-    assert abs(y) < constants.WALL_LIMIT
+
+def test_high_score_label_follows_the_score_label_as_in_the_lecture() -> None:
+    assert constants.HIGH_SCORE_LABEL == "High Score: "
+    assert constants.HIGH_SCORE_LABEL != constants.SCORE_LABEL
+
+
+def test_old_segments_are_parked_outside_the_screen() -> None:
+    x, y = constants.SEGMENT_PARKING_POSITION
+
+    assert abs(x) > HALF_WIDTH
+    assert abs(y) > HALF_HEIGHT

tests/test_main.py

@@ -20,10 +20,10 @@ from snake_game.main import (
     bind_keys,
     configure_screen,
     eat_food_if_close,
-    end_game_if_over,
     main,
     play_frame,
     register_head_shape,
+    reset_if_collision,
 )
 from snake_game.snake import Snake
 
@@ -276,7 +276,7 @@ def test_main_lets_the_snake_eat_the_food_that_lies_on_its_way(
         ("goto", (20, 0)),
         ("goto", (constants.WALL_LIMIT, constants.WALL_LIMIT)),
     ]
-    assert scoreboard.calls[-1][1][0] == "Score: 1"
+    assert scoreboard.calls[-1][1][0] == "Score: 1 High Score: 0"
     assert new_segment.position() == (-20, 0)  # where the last segment was
 
 
@@ -288,86 +288,93 @@ def test_main_does_not_raise_the_score_when_the_food_is_far_away(
     main()
 
     scoreboard = turtles[4]
-    assert scoreboard.calls[-1][1][0] == "Score: 0"
+    assert scoreboard.calls[-1][1][0] == "Score: 0 High Score: 0"
     assert len(turtles) == len(constants.STARTING_POSITIONS) + 2
 
 
-def test_the_game_is_not_over_while_the_snake_is_inside_and_clear_of_its_tail() -> None:
-    snake, _ = make_snake()
+def test_nothing_is_reset_while_the_snake_is_inside_and_clear_of_its_tail() -> None:
+    snake, created = make_snake()
     scoreboard = FakeScoreboard()
 
-    assert not end_game_if_over(snake, scoreboard)
-    assert scoreboard.game_overs == 0
+    assert not reset_if_collision(snake, scoreboard)
+    assert scoreboard.resets == 0
+    assert len(created) == len(constants.STARTING_POSITIONS)
 
 
-def test_the_game_is_over_when_the_head_passes_the_wall() -> None:
-    snake, _ = make_snake()
+def test_the_game_is_reset_when_the_head_passes_the_wall() -> None:
+    snake, created = make_snake()
     snake.head.goto(constants.WALL_LIMIT + 1, 0)
     scoreboard = FakeScoreboard()
 
-    assert end_game_if_over(snake, scoreboard)
-    assert scoreboard.game_overs == 1
+    assert reset_if_collision(snake, scoreboard)
+    assert scoreboard.resets == 1
+    assert len(created) == 2 * len(constants.STARTING_POSITIONS)
 
 
-def test_the_game_is_over_when_the_head_touches_the_tail() -> None:
+def test_the_game_is_reset_when_the_head_touches_the_tail() -> None:
     snake, created = make_snake()
     created[1].goto(3, 4)
     scoreboard = FakeScoreboard()
 
-    assert end_game_if_over(snake, scoreboard)
-    assert scoreboard.game_overs == 1
+    assert reset_if_collision(snake, scoreboard)
+    assert scoreboard.resets == 1
+    assert snake.head is not created[0]
 
 
-def test_main_ends_the_game_at_the_wall_shows_game_over_and_waits_for_a_click(
+def test_main_goes_on_after_the_wall_with_a_new_snake_and_no_game_over(
     monkeypatch: pytest.MonkeyPatch, sleeps: list[float]
 ) -> None:
-    turtles, screens = install_fake_turtle(monkeypatch, frames_before_close=100)
+    moves_to_pass_the_wall = constants.WALL_LIMIT // constants.MOVE_DISTANCE + 1
+    turtles, screens = install_fake_turtle(
+        monkeypatch, frames_before_close=moves_to_pass_the_wall + 2
+    )
 
     main()
 
-    snake_head, scoreboard = turtles[0], turtles[4]
-    moves_to_pass_the_wall = constants.WALL_LIMIT // constants.MOVE_DISTANCE + 1
-    assert snake_head.call_names().count("forward") == moves_to_pass_the_wall
-    assert snake_head.position() == (
-        constants.MOVE_DISTANCE * moves_to_pass_the_wall,
-        0,
-    )
+    old_head, scoreboard = turtles[0], turtles[4]
+    new_head = turtles[5]
+    written = [call[1][0] for call in scoreboard.calls if call[0] == "write"]
+    assert old_head.position() == constants.SEGMENT_PARKING_POSITION
+    assert new_head.call_names().count("forward") == 2
+    assert new_head.position() == (2 * constants.MOVE_DISTANCE, 0)
     assert scoreboard.calls[-1] == (
         "write",
-        ("GAME OVER", "center", ("Arial", 24, "normal")),
+        ("Score: 0 High Score: 0", "center", ("Arial", 24, "normal")),
     )
-    assert screens[0].call_names()[-2:] == ["update", "exitonclick"]
-    assert screens[0].call_names().count("exitonclick") == 1
-    assert sleeps == [constants.REFRESH_DELAY_SECONDS] * moves_to_pass_the_wall
+    assert "GAME OVER" not in written
+    assert "exitonclick" not in screens[0].call_names()
 
 
-def test_main_ends_the_game_when_the_snake_touches_its_tail(
+def test_main_shows_the_best_score_after_a_reset(
+    monkeypatch: pytest.MonkeyPatch, sleeps: list[float]
+) -> None:
+    script_randint(monkeypatch, [20, 0])  # the first food lies one move ahead
+    moves_to_pass_the_wall = constants.WALL_LIMIT // constants.MOVE_DISTANCE + 1
+    turtles, _ = install_fake_turtle(
+        monkeypatch, frames_before_close=moves_to_pass_the_wall
+    )
+
+    main()
+
+    scoreboard = turtles[4]
+    assert scoreboard.calls[-1][1][0] == "Score: 0 High Score: 1"
+
+
+def test_main_resets_when_the_snake_touches_its_tail(
     monkeypatch: pytest.MonkeyPatch, sleeps: list[float]
 ) -> None:
     monkeypatch.setattr("snake_game.snake.Snake.hits_tail", lambda self: True)
-    turtles, screens = install_fake_turtle(monkeypatch, frames_before_close=100)
+    turtles, screens = install_fake_turtle(monkeypatch, frames_before_close=2)
 
     main()
 
     assert turtles[0].call_names().count("forward") == 1
-    assert turtles[4].calls[-1][1][0] == "GAME OVER"
-    assert screens[0].call_names()[-1] == "exitonclick"
-
-
-def test_main_does_not_move_the_snake_after_game_over(
-    monkeypatch: pytest.MonkeyPatch, sleeps: list[float]
-) -> None:
-    turtles, screens = install_fake_turtle(monkeypatch, frames_before_close=100)
-
-    main()
-
-    updates = screens[0].call_names().count("update")
-    moves = turtles[0].call_names().count("forward")
-    assert updates == moves + 1  # one update per frame, and one for the last text
+    assert turtles[0].position() == constants.SEGMENT_PARKING_POSITION
+    assert "exitonclick" not in screens[0].call_names()
 
 
 @pytest.mark.parametrize("closing_error", [FakeTerminatorError, FakeTclError])
-def test_main_ends_quietly_when_the_window_is_closed_after_game_over(
+def test_main_ends_quietly_when_the_window_is_closed_after_a_reset(
     monkeypatch: pytest.MonkeyPatch,
     sleeps: list[float],
     closing_error: type[Exception],
@@ -381,7 +388,7 @@ def test_main_ends_quietly_when_the_window_is_closed_after_game_over(
 
     main()
 
-    assert turtles[4].calls[-1][1][0] == "GAME OVER"
+    assert turtles[4].calls[-1][1][0] == "Score: 0 High Score: 0"
     assert "exitonclick" not in screens[0].call_names()
 
 

tests/test_scoreboard.py

@@ -8,7 +8,10 @@ import pytest
 from fakes import install_fake_turtle, make_scoreboard
 from snake_game import constants
 
-START_TEXT = ("write", ("Score: 0", "center", ("Arial", 24, "normal")))
+START_TEXT = (
+    "write",
+    ("Score: 0 High Score: 0", "center", ("Arial", 24, "normal")),
+)
 
 
 def test_scoreboard_is_white_hidden_and_at_the_top_centre(
@@ -29,7 +32,7 @@ def test_scoreboard_inherits_from_turtle(monkeypatch: pytest.MonkeyPatch) -> Non
     assert issubclass(module.Scoreboard, sys.modules["turtle"].Turtle)
 
 
-def test_scoreboard_starts_by_writing_score_0_centred_in_arial_24(
+def test_scoreboard_starts_by_writing_both_scores_0_centred_in_arial_24(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     scoreboard = make_scoreboard(monkeypatch)
@@ -47,7 +50,7 @@ def test_increase_score_wipes_the_old_text_and_writes_the_new_score(
     assert scoreboard.call_names()[-2:] == ["clear", "write"]
     assert scoreboard.calls[-1] == (
         "write",
-        ("Score: 1", "center", ("Arial", 24, "normal")),
+        ("Score: 1 High Score: 0", "center", ("Arial", 24, "normal")),
     )
 
 
@@ -57,29 +60,78 @@ def test_every_food_adds_one_to_the_score(monkeypatch: pytest.MonkeyPatch) -> No
     for _ in range(3):
         scoreboard.increase_score()
 
-    assert scoreboard.calls[-1][1][0] == "Score: 3"
+    assert scoreboard.calls[-1][1][0] == "Score: 3 High Score: 0"
 
 
-def test_game_over_writes_the_text_at_the_centre_in_the_scoreboard_font(
+def test_high_score_starts_at_0(monkeypatch: pytest.MonkeyPatch) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    assert scoreboard.high_score == 0
+    assert scoreboard.score == 0
+
+
+def test_reset_keeps_a_higher_score_as_the_high_score_and_starts_again(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     scoreboard = make_scoreboard(monkeypatch)
+    for _ in range(3):
+        scoreboard.increase_score()
 
-    scoreboard.game_over()
+    scoreboard.reset()
 
-    assert scoreboard.calls[-2:] == [
-        ("goto", constants.GAME_OVER_POSITION),
-        ("write", ("GAME OVER", "center", ("Arial", 24, "normal"))),
-    ]
+    assert scoreboard.high_score == 3
+    assert scoreboard.score == 0
+    assert scoreboard.call_names()[-2:] == ["clear", "write"]
+    assert scoreboard.calls[-1] == (
+        "write",
+        ("Score: 0 High Score: 3", "center", ("Arial", 24, "normal")),
+    )
 
 
-def test_game_over_leaves_the_score_on_the_screen(
+def test_reset_keeps_the_high_score_when_the_score_is_lower(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+    for _ in range(3):
+        scoreboard.increase_score()
+    scoreboard.reset()
+    scoreboard.increase_score()
+
+    scoreboard.reset()
+
+    assert scoreboard.high_score == 3
+    assert scoreboard.calls[-1][1][0] == "Score: 0 High Score: 3"
+
+
+def test_reset_keeps_the_high_score_when_the_score_is_equal(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
     scoreboard = make_scoreboard(monkeypatch)
     scoreboard.increase_score()
-    calls_before = len(scoreboard.calls)
+    scoreboard.reset()
+    scoreboard.increase_score()
 
-    scoreboard.game_over()
+    scoreboard.reset()
 
-    assert "clear" not in scoreboard.call_names()[calls_before:]
+    assert scoreboard.high_score == 1
+    assert scoreboard.score == 0
+
+
+def test_the_score_text_shows_both_scores_while_playing(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+    scoreboard.increase_score()
+    scoreboard.increase_score()
+    scoreboard.reset()
+    scoreboard.increase_score()
+
+    assert scoreboard.calls[-1][1][0] == "Score: 1 High Score: 2"
+
+
+def test_scoreboard_has_no_game_over_any_more(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    assert not hasattr(scoreboard, "game_over")

tests/test_snake.py

@@ -407,3 +407,61 @@ def test_a_snake_of_four_segments_cannot_touch_its_tail_in_a_small_square() -> N
         snake.move()
 
     assert not snake.hits_tail()
+
+
+def test_reset_sends_every_old_segment_off_the_screen() -> None:
+    snake, created = make_snake()
+    snake.extend()
+    old = list(created)
+
+    snake.reset()
+
+    assert len(old) == len(constants.STARTING_POSITIONS) + 1
+    assert all(
+        segment.position() == constants.SEGMENT_PARKING_POSITION for segment in old
+    )
+
+
+def test_reset_makes_the_snake_again_at_the_starting_positions() -> None:
+    snake, created = make_snake()
+    snake.extend()
+    snake.extend()
+    old_count = len(created)
+
+    snake.reset()
+
+    assert len(snake.segments) == len(constants.STARTING_POSITIONS)
+    assert positions(snake.segments) == [
+        (float(x), float(y)) for x, y in constants.STARTING_POSITIONS
+    ]
+    assert snake.segments == created[old_count:]
+
+
+def test_reset_makes_the_first_new_segment_the_head() -> None:
+    snake, created = make_snake()
+    old_head = snake.head
+
+    snake.reset()
+
+    new_head = created[len(constants.STARTING_POSITIONS)]
+    assert snake.head is snake.segments[0] is new_head
+    assert snake.head is not old_head
+    assert ("shape", (constants.HEAD_SHAPE,)) in new_head.calls
+
+
+def test_reset_snake_moves_right_from_the_starting_positions() -> None:
+    snake, _ = make_snake_moving(constants.UP)
+
+    snake.reset()
+    snake.move()
+
+    assert snake.head.position() == (constants.MOVE_DISTANCE, 0)
+
+
+def test_reset_forgets_the_direction_of_the_last_move() -> None:
+    snake, _ = make_snake_moving(constants.DOWN)
+
+    snake.reset()
+    snake.up()  # allowed again: the new snake moves right, not down
+
+    assert snake.head.heading() == constants.UP