def test_center():
"""Test getting and setting the center."""
circle = Circle(1)
assert all(circle.center == (0, 0, 0))
center = (1, 1, 1)
circle.center = center
assert all(circle.center == center)
def test_moment_inertia(r, center):
circle = Circle(r)
assert np.all(np.asarray(circle.planar_moments_inertia) >= 0)
circle.center = center
area = np.pi * r ** 2
expected = [np.pi / 4 * r ** 4] * 3
expected[0] += area * center[0] ** 2
expected[1] += area * center[1] ** 2
expected[2] = area * center[0] * center[1]
np.testing.assert_allclose(circle.planar_moments_inertia[:2], expected[:2])
np.testing.assert_allclose(circle.planar_moments_inertia[2], expected[2])
assert circle.polar_moment_inertia == pytest.approx(sum(expected[:2]))
def test_inertia_tensor():
"""Test the inertia tensor calculation."""
circle = Circle(1)
circle.center = (0, 0, 0)
assert np.sum(circle.inertia_tensor > 1e-6) == 1
assert circle.inertia_tensor[2, 2] == np.pi / 2