Fix cars drawn vertically: register shapes in the turtle shape frame

Task: MIL-004#1

tests/test_car_shape.py

@@ -1,8 +1,13 @@
 """Tests for the car drawing."""
 
-from turtle import TurtleScreen
+from turtle import Turtle, TurtleScreen
 
-from car_shape import car_components, register_car_shapes, shape_name
+from car_shape import (
+    car_components,
+    register_car_shapes,
+    shape_name,
+    to_shape_frame,
+)
 from constants import CAR_HEIGHT, CAR_LENGTH, COLORS
 
 
@@ -28,3 +33,30 @@ def test_body_and_cabin_use_the_car_colour() -> None:
 def test_register_car_shapes_adds_one_shape_per_colour(screen: TurtleScreen) -> None:
     register_car_shapes(screen)
     assert all(shape_name(color) in screen.getshapes() for color in COLORS)
+
+
+def test_to_shape_frame_maps_screen_points_to_the_upright_shape_frame() -> None:
+    assert to_shape_frame((-20, 0)) == (0, -20)  # front (screen left) -> shape -y
+    assert to_shape_frame((20, 0)) == (0, 20)
+    assert to_shape_frame((0, 10)) == (-10, 0)
+    assert to_shape_frame((0, 0)) == (0, 0)
+
+
+def test_drawn_car_is_horizontal(screen: TurtleScreen) -> None:
+    register_car_shapes(screen)
+    car = Turtle(visible=False)
+    car.penup()
+    car.shape(shape_name("red"))
+    car.showturtle()
+    try:
+        screen.update()
+        canvas = screen.getcanvas()
+        # the first compound component is the lower body
+        coords = canvas.coords(car.turtle._item[0])  # type: ignore[attr-defined]
+        xs, ys = coords[0::2], coords[1::2]
+        width, height = max(xs) - min(xs), max(ys) - min(ys)
+        assert width > height
+        assert width <= CAR_LENGTH
+        assert height <= CAR_HEIGHT
+    finally:
+        car.hideturtle()