def test_atoms_extend__on_nonbonded_structure_reindexes_new_bonds_to_proper_atoms(
linear_cnnc):
linear_cnnc_no_bonds = Atoms(elements='CNNC',
positions=[(0., 0., 0), (1.0, 0., 0.),
(2.0, 0., 0.), (3.0, 0., 0.)])
linear_cnnc_no_bonds.extend(linear_cnnc)
assert np.array_equal(linear_cnnc_no_bonds.bonds, [(4, 5), (5, 6), (6, 7)])
def test_atoms_extend__new_types_come_after_old_types1(linear_cnnc):
a = Atoms(elements="C", positions=[[0, 0, 0]])
b = Atoms(elements="H", positions=[[1, 1, 1]])
a.extend(b)
assert np.array_equal(a.elements, ["C", "H"])
