Turn snake towards sides with arrow keys

(but not backwards)

game.py

@@ -22,3 +22,17 @@ def update(self):
             self.snake.x -= 1
         elif self.snake.orientation == 'right':
             self.snake.x += 1
+
+    def request_orientation(self, requested_orientation):
+        current_orientation = self.snake.orientation
+
+        if current_orientation == 'up' and requested_orientation == 'down':
+            return
+        if current_orientation == 'down' and requested_orientation == 'up':
+            return
+        if current_orientation == 'left' and requested_orientation == 'right':
+            return
+        if current_orientation == 'right' and requested_orientation == 'left':
+            return
+
+        self.snake.set_orientation(requested_orientation)

main.py

@@ -38,6 +38,20 @@ def on_draw(self):
         }
         draw_snake_head(snake_head_canvas, self.game.snake.orientation)
 
+    def on_key_press(self, symbol, modifiers):
+        requested_orientation = None
+        if symbol == arcade.key.DOWN:
+            requested_orientation = 'down'
+        elif symbol == arcade.key.UP:
+            requested_orientation = 'up'
+        elif symbol == arcade.key.LEFT:
+            requested_orientation = 'left'
+        elif symbol == arcade.key.RIGHT:
+            requested_orientation = 'right'
+
+        if requested_orientation:
+            self.game.request_orientation(requested_orientation)
+
 
 def main():
     window = GameWindow()

test_game.py

@@ -44,3 +44,59 @@ def test_when_update_while_facing_right_then_snake_moves_forward(self):
         game.update()
         assert 6 == game.snake.x
         assert 5 == game.snake.y
+
+    def test_when_requesting_orientation_to_the_sides_then_snake_turns(self):
+        game = Game(10)
+        game.initialize_snake()
+
+        game.snake.set_orientation('down')
+        game.request_orientation('left')
+        assert 'left' == game.snake.orientation
+
+        game.snake.set_orientation('down')
+        game.request_orientation('right')
+        assert 'right' == game.snake.orientation
+
+        game.snake.set_orientation('up')
+        game.request_orientation('left')
+        assert 'left' == game.snake.orientation
+
+        game.snake.set_orientation('up')
+        game.request_orientation('right')
+        assert 'right' == game.snake.orientation
+
+        game.snake.set_orientation('left')
+        game.request_orientation('up')
+        assert 'up' == game.snake.orientation
+
+        game.snake.set_orientation('left')
+        game.request_orientation('down')
+        assert 'down' == game.snake.orientation
+
+        game.snake.set_orientation('right')
+        game.request_orientation('up')
+        assert 'up' == game.snake.orientation
+
+        game.snake.set_orientation('right')
+        game.request_orientation('down')
+        assert 'down' == game.snake.orientation
+
+    def test_when_requesting_orientation_backwards_then_snake_doesnt_turn(self):
+        game = Game(10)
+        game.initialize_snake()
+
+        game.snake.set_orientation('down')
+        game.request_orientation('up')
+        assert 'down' == game.snake.orientation
+
+        game.snake.set_orientation('up')
+        game.request_orientation('down')
+        assert 'up' == game.snake.orientation
+
+        game.snake.set_orientation('right')
+        game.request_orientation('left')
+        assert 'right' == game.snake.orientation
+
+        game.snake.set_orientation('left')
+        game.request_orientation('right')
+        assert 'left' == game.snake.orientation