def test_isolation_3D(): atoms = FaceCenteredCubic(size=(2, 2, 2), symbol='Cu', pbc=(1, 1, 1)) result = isolate_components(atoms) assert len(result) == 1 key, components = list(result.items())[0] assert key == '3D' assert len(components) == 1 bulk = components[0] assert bulk.get_chemical_formula() == atoms.get_chemical_formula()