src/snake_game/scoreboard.py

@@ -0,0 +1,58 @@
+"""! @file
+@brief The scoreboard: the text at the top of the screen that shows the score.
+
+The class follows the day-21 lecture on inheritance: `Scoreboard` is a `Turtle`
+that writes text. Like `food`, this module needs `turtle` when it is imported;
+the game imports it only when it starts, and the tests install a fake `turtle`
+module first.
+"""
+
+from turtle import Turtle
+
+from snake_game.constants import (
+    GAME_OVER_POSITION,
+    GAME_OVER_TEXT,
+    SCORE_LABEL,
+    SCOREBOARD_ALIGNMENT,
+    SCOREBOARD_COLOR,
+    SCOREBOARD_FONT,
+    SCOREBOARD_POSITION,
+)
+
+
+class Scoreboard(Turtle):
+    """! @brief Shows the score as text at the top centre of the screen."""
+
+    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.
+        self.score = 0
+        self.color(SCOREBOARD_COLOR)
+        self.penup()
+        self.hideturtle()
+        self.goto(SCOREBOARD_POSITION)
+        self.update_scoreboard()
+
+    def update_scoreboard(self) -> None:
+        """! @brief Wipe the old text and write the label and the score."""
+        self.clear()
+        self.write(
+            f"{SCORE_LABEL}{self.score}",
+            align=SCOREBOARD_ALIGNMENT,
+            font=SCOREBOARD_FONT,
+        )
+
+    def increase_score(self) -> None:
+        """! @brief Add 1 to the score and write it."""
+        self.score += 1
+        self.update_scoreboard()
+
+    def game_over(self) -> None:
+        """! @brief Write the game-over text at the centre of the screen.
+
+        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.
+        """
+        self.goto(GAME_OVER_POSITION)
+        self.write(GAME_OVER_TEXT, align=SCOREBOARD_ALIGNMENT, font=SCOREBOARD_FONT)

tests/test_scoreboard.py

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+"""Tests of the scoreboard, with a fake `Turtle` as its base class."""
+
+import importlib
+import sys
+
+import pytest
+
+from fakes import install_fake_turtle, make_scoreboard
+from snake_game import constants
+
+START_TEXT = ("write", ("Score: 0", "center", ("Arial", 24, "normal")))
+
+
+def test_scoreboard_is_white_hidden_and_at_the_top_centre(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    assert ("color", ("white",)) in scoreboard.calls
+    assert "penup" in scoreboard.call_names()
+    assert "hideturtle" in scoreboard.call_names()
+    assert ("goto", constants.SCOREBOARD_POSITION) in scoreboard.calls
+
+
+def test_scoreboard_inherits_from_turtle(monkeypatch: pytest.MonkeyPatch) -> None:
+    install_fake_turtle(monkeypatch)
+    module = importlib.import_module("snake_game.scoreboard")
+
+    assert issubclass(module.Scoreboard, sys.modules["turtle"].Turtle)
+
+
+def test_scoreboard_starts_by_writing_score_0_centred_in_arial_24(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    assert scoreboard.calls[-1] == START_TEXT
+
+
+def test_increase_score_wipes_the_old_text_and_writes_the_new_score(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    scoreboard.increase_score()
+
+    assert scoreboard.call_names()[-2:] == ["clear", "write"]
+    assert scoreboard.calls[-1] == (
+        "write",
+        ("Score: 1", "center", ("Arial", 24, "normal")),
+    )
+
+
+def test_every_food_adds_one_to_the_score(monkeypatch: pytest.MonkeyPatch) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    for _ in range(3):
+        scoreboard.increase_score()
+
+    assert scoreboard.calls[-1][1][0] == "Score: 3"
+
+
+def test_game_over_writes_the_text_at_the_centre_in_the_scoreboard_font(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+
+    scoreboard.game_over()
+
+    assert scoreboard.calls[-2:] == [
+        ("goto", constants.GAME_OVER_POSITION),
+        ("write", ("GAME OVER", "center", ("Arial", 24, "normal"))),
+    ]
+
+
+def test_game_over_leaves_the_score_on_the_screen(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    scoreboard = make_scoreboard(monkeypatch)
+    scoreboard.increase_score()
+    calls_before = len(scoreboard.calls)
+
+    scoreboard.game_over()
+
+    assert "clear" not in scoreboard.call_names()[calls_before:]