old_contents: def test_rover_init_with_default_parameters():
      from rover import Rover
      rover = Rover()
      assert rover.x == 0
      assert rover.y == 0
      assert rover.direction == 'N'
  
  def test_rover_init_with_custom_parameters():
      from rover import Rover
      rover = Rover(3, 7, 'W')
      assert rover.x == 3
      assert rover.y == 7
      assert rover.direction == 'W'
  
  
  def test_rover_init_custom_grid():
      from rover import Rover
      rover = Rover(grid_x=100, grid_y=150)
      assert rover.x == 0
      assert rover.y == 0
      assert rover.direction == 'N'
  
      assert rover.grid_x == 100
      assert rover.grid_y == 150
  
  
  def test_rover_init_full_custom_grid():
      from rover import Rover
      rover = Rover(5, 9, 'E', 100, 150)
      assert rover.x == 5
      assert rover.y == 9
      assert rover.direction == 'E'
  
      assert rover.grid_x == 100
      assert rover.grid_y == 150
  
new_contents: def test_rover_init_with_default_parameters():
      from rover import Rover
      rover = Rover()
      assert rover.x == 0
      assert rover.y == 0
      assert rover.direction == 'N'
  
      assert rover.grid_x == 50
      assert rover.grid_y == 50
  
  def test_rover_init_with_custom_parameters():
      from rover import Rover
      rover = Rover(3, 7, 'W')
      assert rover.x == 3
      assert rover.y == 7
      assert rover.direction == 'W'
  
      assert rover.grid_x == 50
      assert rover.grid_y == 50
  
  
  def test_rover_init_custom_grid():
      from rover import Rover
      rover = Rover(grid_x=100, grid_y=150)
      assert rover.x == 0
      assert rover.y == 0
      assert rover.direction == 'N'
  
      assert rover.grid_x == 100
      assert rover.grid_y == 150
  
  
  def test_rover_init_full_custom_grid():
      from rover import Rover
      rover = Rover(5, 9, 'E', 100, 150)
      assert rover.x == 5
      assert rover.y == 9
      assert rover.direction == 'E'
  
      assert rover.grid_x == 100
      assert rover.grid_y == 150
  
subject: Add testing for default grid_* values