new_contents: import pytest
  
  # Skip these tests if we can't import bullet.
  bullet = pytest.importorskip("panda3d.bullet")
  from panda3d import core
  
  
  def reconstruct(object):
      # Create a temporary buffer, which we first write the object into, and
      # subsequently read it from again.
      buffer = core.DatagramBuffer()
  
      writer = core.BamWriter(buffer)
      writer.init()
      writer.write_object(object)
  
      reader = core.BamReader(buffer)
      reader.init()
      object = reader.read_object()
      reader.resolve()
      return object
  
  
  def test_box_shape():
      shape = bullet.BulletBoxShape((1, 2, 3))
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.half_extents_without_margin == shape2.half_extents_without_margin
      assert shape.half_extents_with_margin == shape2.half_extents_with_margin
  
  
  def test_capsule_shape():
      shape = bullet.BulletCapsuleShape(1.4, 3.5, bullet.Y_up)
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.radius == shape2.radius
      assert shape.height == shape2.height
  
  
  def test_cone_shape():
      shape = bullet.BulletConeShape(1.4, 3.5, bullet.Y_up)
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.radius == shape2.radius
      assert shape.height == shape2.height
  
  
  def test_cylinder_shape():
      shape = bullet.BulletCylinderShape(1.4, 3.5, bullet.Y_up)
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.radius == shape2.radius
      assert shape.half_extents_without_margin == shape2.half_extents_without_margin
      assert shape.half_extents_with_margin == shape2.half_extents_with_margin
  
  
  def test_minkowski_sum_shape():
      box = bullet.BulletBoxShape((1, 2, 3))
      sphere = bullet.BulletSphereShape(2.0)
  
      shape = bullet.BulletMinkowskiSumShape(box, sphere)
      shape.transform_a = core.TransformState.make_pos((8, 7, 3))
      shape.transform_b = core.TransformState.make_hpr((45, -10, 110))
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.transform_a.compare_to(shape2.transform_a, True) == 0
      assert shape.transform_b.compare_to(shape2.transform_b, True) == 0
      assert type(shape.shape_a) == type(shape2.shape_a)
      assert type(shape.shape_b) == type(shape2.shape_b)
  
  
  def test_multi_sphere_shape():
      shape = bullet.BulletMultiSphereShape([(1, 2, 3), (4, 5, 6)], [1.5, 2.5])
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.sphere_count == shape2.sphere_count
      assert tuple(shape.sphere_pos) == tuple(shape2.sphere_pos)
      assert tuple(shape.sphere_radius) == tuple(shape2.sphere_radius)
  
  
  def test_plane_shape():
      shape = bullet.BulletPlaneShape((1.2, 0.2, 0.5), 2.5)
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.plane_normal == shape2.plane_normal
      assert shape.plane_constant == shape2.plane_constant
  
  
  def test_sphere_shape():
      shape = bullet.BulletSphereShape(1.4)
      shape.margin = 0.5
  
      shape2 = reconstruct(shape)
  
      assert type(shape) is type(shape2)
      assert shape.margin == shape2.margin
      assert shape.name == shape2.name
      assert shape.radius == shape2.radius
  
subject: add unit tests for bullet bam serializability