import ase
from ase.calculators.lj import LennardJones
from ase.constraints import FixBondLength
from ase.optimize import FIRE

for wrap in [False, True]:
    a = ase.Atoms('CCC',
                  positions=[[1, 0, 5],
                             [0, 1, 5],
                             [-1, 0.5, 5]],
                  cell=[10, 10, 10],
                  pbc=True)
    
    if wrap:
        a.set_scaled_positions(a.get_scaled_positions() % 1.0)
    a.set_calculator(LennardJones())
    a.set_constraint(FixBondLength(0, 2))

    d1 = a.get_distance(0, 2, mic=True)

    FIRE(a, logfile=None).run(fmax=0.01)
    e = a.get_potential_energy()
    d2 = a.get_distance(0, 2, mic=True)
    assert abs(e - -2.034988) < 1e-6
    assert abs(d1 - d2) < 1e-6